CVE-2026-19773:
libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability. The specific flaw exists within the parsing of HTTP/2 HPACK path header. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-31036.
3 issues postponed or untriaged:
CVE-2025-11677:
(needs triaging)
Use After Free in WebSocket server implementation in lws_handshake_server in warmcat libwebsockets may allow an attacker, in specific configurations where the user provides a callback function that handles LWS_CALLBACK_HTTP_CONFIRM_UPGRADE, to achieve denial of service.
CVE-2025-11678:
(needs triaging)
Stack-based Buffer Overflow in lws_adns_parse_label in warmcat libwebsockets allows, when the LWS_WITH_SYS_ASYNC_DNS flag is enabled during compilation, to overflow the label_stack, when the attacker is able to sniff a DNS request in order to craft a response with a matching id containing a label longer than the maximum.
CVE-2026-10650:
(needs triaging)
A flaw has been found in warmcat libwebsockets up to 4.5.8. This issue affects the function lws_ssh_parse_plaintext of the file plugins/protocol_lws_ssh_base/sshd.c of the component SSH Protocol Handler. Executing a manipulation of the argument msg_len can lead to resource consumption. The attack may be launched remotely. The exploit has been published and may be used. This patch is called 3f9f0c6ecaf0e6f3f219d30632c5d1f2479d7498. A patch should be applied to remediate this issue.
Among the 7 debian patches
available in version 4.3.5-7 of the package,
we noticed the following issues:
6 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.
Standards version of the package is outdated.
wishlist
The package should be updated to follow the last version of Debian Policy
(Standards-Version 4.7.4 instead of
4.7.2).
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.
![[bug history graph]](https://qa.debian.org/data/bts/graphs/libw/libwebsockets.png){kind=link}