CVE-2026-53181 | vsock/vmci: fix sk_ack_backlog leak on failed handshake

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.

Published: 2026-06-25 Last update: 2026-07-06 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-53181 is rated Low Risk (22.9/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.13%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2026-53181

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-07-07 0.18% 0.13% -0.06%
2 2026-06-25 — 0.18% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-53181

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 3.6 [email protected]

Weakness enumeration for CVE-2026-53181

GitHub Security Advisory for CVE-2026-53181

GHSA-6gq6-hxjh-9grq · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: vsock/vmci: fix...

OS Trackers for CVE-2026-53181

vendor priority summary link
debian not yet assigned CVE-2026-53181 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2026-53181
suse medium CVE-2026-53181 severity moderate: SUSE including 4 source package names (kernel-default, kernel-default-base, kernel-default-devel, kernel-source), 4 product×package rows across 1 product lines (SUSE Linux Enterprise Server 11 SP4 LTSS EXTREME CORE): Known Not Affected 4. https://www.suse.com/security/cve/CVE-2026-53181/
ubuntu medium CVE-2026-53181 medium priority: Ubuntu including 162 source packages (linux, linux-allwinner-5.19, …), 1458 status rows across 9 suites (bionic, focal, jammy, noble, questing, resolute, trusty, upstream, xenial): DNE 1051, ignored 176, needed 143, released 88. https://ubuntu.com/security/CVE-2026-53181

Affected software / configurations for CVE-2026-53181

Vendor Product Version Raw CPE
linux linux_kernel >= 3.9, < 5.10.259 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.15.210 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.176 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.143 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.94 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.18.36 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.19, < 7.0.13 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc4:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:*
linux linux_kernel 7.1 cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:*

References for CVE-2026-53181

cvelogic Threat Intelligence