CVE-2026-53181: Linux kernel · vsock/vmci: fix sk_ack_backlog leak on failed handshake
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in ea0b03d52881c12a8c634ea0d6cbfa61cefdb488 : update Linux kernel when convenient.
Data as of 6 Nov 2026, 16:49 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-06.
- Patch
- Available – fixed in ea0b03d52881c12a8c634ea0d6cbfa61cefdb488, dfd853197615d322d3a88dbcab91fc0fd2096219, cf7090e255d74c4b61c51f8ede9fcacdd8393b5b +5
Exploitation evidence
Disclosed: evidence found.
CVE published 25 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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.
References
- git.kernel.org/stable/c/22c587aa3ab1ab5264daff3ec32136fd30436c13 (opens in a new tab)
- git.kernel.org/stable/c/cf7090e255d74c4b61c51f8ede9fcacdd8393b5b (opens in a new tab)
- git.kernel.org/stable/c/ea0b03d52881c12a8c634ea0d6cbfa61cefdb488 (opens in a new tab)
- git.kernel.org/stable/c/dfd853197615d322d3a88dbcab91fc0fd2096219 (opens in a new tab)
- git.kernel.org/stable/c/bcb275626055df7f8f947f1a349754b4004d9a15 (opens in a new tab)
- git.kernel.org/stable/c/ba9ad6015937a5e46ba1a31370e3efdec8abbdcc (opens in a new tab)
- git.kernel.org/stable/c/9698582a4dd9c4a05889d7db96d4c0edc9e69cac (opens in a new tab)
- git.kernel.org/stable/c/c05fa14db43ebef3bd862ca9d073981c0358b3f0 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)