CVE-2025-21669: vsock/virtio: discard packets if the transport changes

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-01-31 · updated 2026-07-30
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: vsock/virtio: discard packets if the transport changes If the socket has been de-assigned or assigned to another transport, we must discard any packets received because they are not expected and would cause issues when we access vsk->transport. A possible scenario is described by Hyunwoo Kim in the attached link, where after a first connect() interrupted by a signal, and a second connect() failed, we can find `vsk->transport` at NULL, leading to a NULL pointer dereference.

Affected products

Linux kernel: from 5.5 before 5.15.177; from 5.16 before 6.1.127; from 6.2 before 6.6.74; from 6.7 before 6.12.11; 6.13-rc1, 6.13-rc2, 6.13-rc3, 6.13-rc4, 6.13-rc5, 6.13-rc6 (+1) — fixed in 5.15.177, 6.1.127, 6.12.11, 6.6.74

How to fix

Upgrade to a fixed version: Linux kernel 5.15.177, 6.1.127, 6.12.11, 6.6.74. Check the vendor advisory for mitigations.

References

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