# CVE-2026-10650: Warmcat libwebsockets resource consumption in SSH Protocol Handler

Source: https://junglewise.ai/threats/cve-2026-10650-warmcat-libwebsockets-resource-consumption-in-ssh-protocol  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-06-02. Updated: 2026-06-02  
License: CC BY 4.0 with a link back

CVE-2026-10650 · Severity: medium · CVSS 5.3 · Published 2026-06-02

A vulnerability exists in the SSH protocol handler of libwebsockets, a networking library used by various applications to manage web and SSH connections. An unauthenticated remote attacker can send a specially crafted small packet that forces the server to allocate a large amount of memory. This can lead to a denial-of-service condition where the server crashes or becomes unresponsive due to memory exhaustion, potentially impacting business operations and service availability.

Technologies: [Warmcat Libwebsockets](https://junglewise.ai/threats/technologies/libwebsockets). Vendors: [Warmcat](https://junglewise.ai/threats/vendors/warmcat).

## Quick answers

**Is CVE-2026-10650 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-10650 being exploited in the wild.

**How severe is CVE-2026-10650?** Medium severity, with a CVSS score of 5.3, published 2 June 2026.

**Which products and versions are affected?** Warmcat Libwebsockets up to 4.5.8.

**Is there a fix for CVE-2026-10650?** A patch was published on 2026-06-02: Patch commit 3f9f0c6ecaf0e6f3f219d30632c5d1f2479d7498 released Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-10650 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-10650?** Check whether you run Warmcat Libwebsockets at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A vulnerability in the SSH protocol plugin of libwebsockets (specifically in `plugins/protocol_lws_ssh_base/sshd.c`) stems from a missing upper-bound check on the `msg_len` argument within the `lws_ssh_parse_plaintext` function. An unauthenticated remote attacker can manipulate the 4-byte `msg_len` field in a pre-authentication packet. When the `msg_id` is set to `SSH_MSG_KEXINIT`, the library uses this unchecked length to perform a heap allocation via `sshd_zalloc` (which calls `malloc` and `memset`). By sending multiple connections with large `msg_len` values, an attacker can trigger the system's Out-Of-Memory (OOM) killer to terminate the server process. A patch (commit 3f9f0c6) introduces `LWS_SSH_MAX_PACKET_SIZE` to enforce a 256KB limit.

## Affected products

- warmcat libwebsockets up to 4.5.8

## Timeline

- 2026-06-02: advisory: NVD publication date
- 2026-06-02: disclosed: Vulnerability details and PoC published by researcher
- 2026-06-02: patched: Patch commit 3f9f0c6ecaf0e6f3f219d30632c5d1f2479d7498 released

## References

- [https://github.com/biniamf/pocs/blob/main/libwebsockets_sshd-parse-ic-unbounded-alloc/poc_sshd_unbounded_alloc.py](https://github.com/biniamf/pocs/blob/main/libwebsockets_sshd-parse-ic-unbounded-alloc/poc_sshd_unbounded_alloc.py)
- [https://github.com/biniamf/pocs/tree/main/libwebsockets_sshd-parse-ic-unbounded-alloc](https://github.com/biniamf/pocs/tree/main/libwebsockets_sshd-parse-ic-unbounded-alloc)
- [https://github.com/warmcat/libwebsockets/](https://github.com/warmcat/libwebsockets/)
- [https://github.com/warmcat/libwebsockets/commit/3f9f0c6ecaf0e6f3f219d30632c5d1f2479d7498](https://github.com/warmcat/libwebsockets/commit/3f9f0c6ecaf0e6f3f219d30632c5d1f2479d7498)
- [https://vuldb.com/cve/CVE-2026-10650](https://vuldb.com/cve/CVE-2026-10650)
- [https://vuldb.com/submit/830261](https://vuldb.com/submit/830261)
- [https://vuldb.com/vuln/367955](https://vuldb.com/vuln/367955)

## Related threats

- [libwebsockets out-of-bounds read in LEJP parser](https://junglewise.ai/threats/cve-2026-95114-libwebsockets-contains-an-out-of-bounds-read-vulnerability-in-the)
- [warmcat libwebsockets out-of-bounds write in LECP CBOR parsing](https://junglewise.ai/threats/cve-2026-78161-warmcat-libwebsockets-out-of-bounds-write-in-lecp-cbor-parsing)