Medium severity · published Jun 25, 2026
CVE-2026-53181
vsock/vmci: fix sk_ack_backlog leak on failed handshake
5.5
CVSS
0.1%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 2% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
KE
Kernel · Linux
3.9 before 5.10.259; 5.11 before 5.15.210; 5.16 before 6.1.176; 6.2 before 6.6.143; 6.7 before 6.12.94; 6.13 before 6.18.36; +7 more · source: NVD
LI
Linux · Linux
d021c344051af91f42c5ba9fdedc176740cbd238 before 22c587aa3ab1ab5264daff3ec32136fd30436c13; d021c344051af91f42c5ba9fdedc176740cbd238 before cf7090e255d74c4b61c51f8ede9fcacdd8393b5b; d021c344051af91f42c5ba9fdedc176740cbd238 before ea0b03d52881c12a8c634ea0d6cbfa61cefdb488; d021c344051af91f42c5ba9fdedc176740cbd238 before dfd853197615d322d3a88dbcab91fc0fd2096219; d021c344051af91f42c5ba9fdedc176740cbd238 before bcb275626055df7f8f947f1a349754b4004d9a15; d021c344051af91f42c5ba9fdedc176740cbd238 before ba9ad6015937a5e46ba1a31370e3efdec8abbdcc; +3 more · source: vendor
SS
SIMATIC S7-1500 TM MFP - GNU/Linux subsystem · Siemens
0 · source: CISA
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-53181
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-53181
Patch
https://git.kernel.org/stable/c/22c587aa3ab1ab5264daff3ec32136fd30436c13
Patch
https://git.kernel.org/stable/c/9698582a4dd9c4a05889d7db96d4c0edc9e69cac
Patch
https://git.kernel.org/stable/c/ba9ad6015937a5e46ba1a31370e3efdec8abbdcc
Patch
https://git.kernel.org/stable/c/bcb275626055df7f8f947f1a349754b4004d9a15
Patch
https://git.kernel.org/stable/c/c05fa14db43ebef3bd862ca9d073981c0358b3f0
Patch
https://git.kernel.org/stable/c/cf7090e255d74c4b61c51f8ede9fcacdd8393b5b
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