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general

source: libssh2 (main)
version: 1.11.1-5
maintainer: Nicolas Mora (DMD)
arch: any
std-ver: 4.7.4
VCS: Git (Browse, QA)

versions [more versions can be listed by madison] [old versions available from snapshot.debian.org]

[pool directory]

o-o-stable: 1.9.0-2+deb11u1
oldstable: 1.10.0-3
stable: 1.11.1-1+deb13u1
stable-sec: 1.11.1-1+deb13u1
testing: 1.11.1-5
unstable: 1.11.1-5

versioned links

1.9.0-2+deb11u1: [.dsc, use dget on this link to retrieve source package] [changelog] [copyright] [rules] [control]
1.10.0-3: [.dsc, use dget on this link to retrieve source package] [changelog] [copyright] [rules] [control]
1.11.1-1+deb13u1: [.dsc, use dget on this link to retrieve source package] [changelog] [copyright] [rules] [control]
1.11.1-5: [.dsc, use dget on this link to retrieve source package] [changelog] [copyright] [rules] [control]

binaries

libssh2-1-dev
libssh2-1t64

action needed

6 security issues in trixie high

There are 6 open security issues in trixie.

6 important issues:

CVE-2026-58050: libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.
CVE-2026-58051: libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.
CVE-2026-66032: libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.
CVE-2026-66033: libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2_cipher_crypt() function in src/openssl.c that allows a malicious SSH server to crash any connecting client by negotiating AES-GCM ciphers during handshake. Attackers can exploit the underflow in the expression computing blocksize minus aadlen minus authentication tag length to trigger an out-of-bounds read and a memcpy call with a near-SIZE_MAX length argument, causing immediate process crash before any authentication occurs.
CVE-2026-66034: libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region.
CVE-2026-66035: libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer overflow vulnerability that allows a malicious SSH server to corrupt heap metadata in any connecting client by sending a packet with a packet_length smaller than the cipher's block size during Encrypt-then-MAC cipher negotiation. In the fullpacket() function in src/transport.c, the ETM path allocates a buffer of packet_length bytes but copies blocksize minus one bytes via memcpy, causing an overflow that on 32-bit glibc writes attacker-controlled bytes into an adjacent chunk's SIZE field, enabling tcache bin confusion, overlapping live objects, and function pointer overwrite during the session handshake before authentication.

Created: 2026-06-28 Last update: 2026-08-02 20:32

2 security issues in sid high

There are 2 open security issues in sid.

2 important issues:

CVE-2026-58050: libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.
CVE-2026-58051: libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.

Created: 2026-06-28 Last update: 2026-08-02 20:32

2 security issues in forky high

There are 2 open security issues in forky.

2 important issues:

CVE-2026-58050: libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.
CVE-2026-58051: libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.

Created: 2026-06-28 Last update: 2026-08-02 20:32

10 security issues in bullseye high

There are 10 open security issues in bullseye.

9 important issues:

CVE-2025-15661: libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.
CVE-2026-55199: libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over 60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not apply to CPU-bound loops.
CVE-2026-55200: libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.
CVE-2026-58050: libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.
CVE-2026-58051: libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.
CVE-2026-66032: libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.
CVE-2026-66033: libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2_cipher_crypt() function in src/openssl.c that allows a malicious SSH server to crash any connecting client by negotiating AES-GCM ciphers during handshake. Attackers can exploit the underflow in the expression computing blocksize minus aadlen minus authentication tag length to trigger an out-of-bounds read and a memcpy call with a near-SIZE_MAX length argument, causing immediate process crash before any authentication occurs.
CVE-2026-66034: libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region.
CVE-2026-66035: libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer overflow vulnerability that allows a malicious SSH server to corrupt heap metadata in any connecting client by sending a packet with a packet_length smaller than the cipher's block size during Encrypt-then-MAC cipher negotiation. In the fullpacket() function in src/transport.c, the ETM path allocates a buffer of packet_length bytes but copies blocksize minus one bytes via memcpy, causing an overflow that on 32-bit glibc writes attacker-controlled bytes into an adjacent chunk's SIZE field, enabling tcache bin confusion, overlapping live objects, and function pointer overwrite during the session handshake before authentication.

1 issue postponed or untriaged:

CVE-2026-7598: (postponed; to be fixed through a stable update) A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the function userauth_password of the file src/userauth.c. Such manipulation of the argument username_len/password_len leads to integer overflow. The attack may be launched remotely. The name of the patch is 256d04b60d80bf1190e96b0ad1e91b2174d744b1. A patch should be applied to remediate this issue.

Created: 2026-06-18 Last update: 2026-08-02 20:32

10 security issues in bookworm high

There are 10 open security issues in bookworm.

9 important issues:

CVE-2025-15661: libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.
CVE-2026-55199: libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over 60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not apply to CPU-bound loops.
CVE-2026-55200: libssh2 through 1.11.1, fixed in commit 7acf3df contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.
CVE-2026-58050: libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.
CVE-2026-58051: libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.
CVE-2026-66032: libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.
CVE-2026-66033: libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2_cipher_crypt() function in src/openssl.c that allows a malicious SSH server to crash any connecting client by negotiating AES-GCM ciphers during handshake. Attackers can exploit the underflow in the expression computing blocksize minus aadlen minus authentication tag length to trigger an out-of-bounds read and a memcpy call with a near-SIZE_MAX length argument, causing immediate process crash before any authentication occurs.
CVE-2026-66034: libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region.
CVE-2026-66035: libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer overflow vulnerability that allows a malicious SSH server to corrupt heap metadata in any connecting client by sending a packet with a packet_length smaller than the cipher's block size during Encrypt-then-MAC cipher negotiation. In the fullpacket() function in src/transport.c, the ETM path allocates a buffer of packet_length bytes but copies blocksize minus one bytes via memcpy, causing an overflow that on 32-bit glibc writes attacker-controlled bytes into an adjacent chunk's SIZE field, enabling tcache bin confusion, overlapping live objects, and function pointer overwrite during the session handshake before authentication.

1 issue postponed or untriaged:

CVE-2026-7598: (needs triaging) A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the function userauth_password of the file src/userauth.c. Such manipulation of the argument username_len/password_len leads to integer overflow. The attack may be launched remotely. The name of the patch is 256d04b60d80bf1190e96b0ad1e91b2174d744b1. A patch should be applied to remediate this issue.

Created: 2026-05-02 Last update: 2026-08-02 20:32

debian/patches: 4 patches to forward upstream low

Among the 10 debian patches available in version 1.11.1-5 of the package, we noticed the following issues:

4 patches where the metadata indicates that the patch has not yet been forwarded upstream. You should either forward the patch upstream or update the metadata to document its real status.

Created: 2026-06-25 Last update: 2026-07-29 12:00

testing migrations

This package will soon be part of the auto-openssl transition. You might want to ensure that your package is ready for it. You can probably find supplementary information in the debian-release archives or in the corresponding release.debian.org bug.

news

[2026-08-01] libssh2 1.11.1-5 MIGRATED to testing (Debian testing watch)
[2026-07-28] Accepted libssh2 1.11.1-5 (source) into unstable (Nicolas Mora)
[2026-06-27] libssh2 1.11.1-4 MIGRATED to testing (Debian testing watch)
[2026-06-25] Accepted libssh2 1.11.1-1+deb13u1 (source) into proposed-updates (Debian FTP Masters) (signed by: Moritz Mühlenhoff)
[2026-06-25] Accepted libssh2 1.11.1-1+deb13u1 (source) into stable-security (Debian FTP Masters) (signed by: Moritz Mühlenhoff)
[2026-06-24] Accepted libssh2 1.11.1-4 (source) into unstable (Nicolas Mora)
[2026-05-18] libssh2 1.11.1-3 MIGRATED to testing (Debian testing watch)
[2026-05-09] Accepted libssh2 1.11.1-3 (source) into unstable (Nicolas Mora)
[2026-03-21] libssh2 1.11.1-2 MIGRATED to testing (Debian testing watch)
[2026-03-18] Accepted libssh2 1.11.1-2 (source) into unstable (Nicolas Mora)
[2024-10-21] libssh2 1.11.1-1 MIGRATED to testing (Debian testing watch)
[2024-10-18] Accepted libssh2 1.11.1-1 (source) into unstable (Nicolas Mora)
[2024-08-05] libssh2 1.11.0-7 MIGRATED to testing (Debian testing watch)
[2024-08-02] Accepted libssh2 1.11.0-7 (source) into unstable (Nicolas Mora)
[2024-07-29] libssh2 1.11.0-6 MIGRATED to testing (Debian testing watch)
[2024-07-25] Accepted libssh2 1.11.0-6 (source) into unstable (Nicolas Mora)
[2024-05-25] libssh2 1.11.0-5 MIGRATED to testing (Debian testing watch)
[2024-05-22] Accepted libssh2 1.11.0-5 (source) into unstable (Nicolas Mora)
[2024-04-25] libssh2 1.11.0-4.1 MIGRATED to testing (Debian testing watch)
[2024-04-23] Accepted libssh2 1.9.0-2+deb11u1 (source) into oldstable-proposed-updates (Debian FTP Masters) (signed by: Nicolas Mora)
[2024-02-28] Accepted libssh2 1.11.0-4.1 (source) into unstable (Graham Inggs)
[2024-02-02] Accepted libssh2 1.11.0-4.1~exp1 (source) into experimental (Steve Langasek)
[2024-01-09] libssh2 1.11.0-4 MIGRATED to testing (Debian testing watch)
[2024-01-02] Accepted libssh2 1.11.0-4 (source) into unstable (Nicolas Mora)
[2023-12-02] libssh2 1.11.0-3 MIGRATED to testing (Debian testing watch)
[2023-11-29] Accepted libssh2 1.11.0-3 (source) into unstable (Nicolas Mora)
[2023-09-08] Accepted libssh2 1.8.0-2.1+deb10u1 (source) into oldoldstable (Guilhem Moulin)
[2023-07-02] libssh2 1.11.0-2 MIGRATED to testing (Debian testing watch)
[2023-06-25] Accepted libssh2 1.11.0-2 (source) into unstable (Nicolas Mora)
[2023-06-05] Accepted libssh2 1.11.0-1 (source) into experimental (Nicolas Mora)

1
2

bugs [bug history graph]

all: 1
RC: 0
I&N: 1
M&W: 0
F&P: 0
patch: 0

links

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buildd: logs, reproducibility, cross
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ubuntu

[Information about Ubuntu for Debian Developers]

version: 1.11.1-4ubuntu1
patches for 1.11.1-4ubuntu1

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