CVE-2025-21666: vsock: prevent null-ptr-deref in vsock_*[has_data|has_space]

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 2026-06-17
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: vsock: prevent null-ptr-deref in vsock_*[has_data|has_space] Recent reports have shown how we sometimes call vsock_*_has_data() when a vsock socket has been de-assigned from a transport (see attached links), but we shouldn't. Previous commits should have solved the real problems, but we may have more in the future, so to avoid null-ptr-deref, we can return 0 (no space, no data available) but with a warning. This way the code should continue to run in a nearly consistent state and have a warning that allows us to debug future problems.

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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