CVE-2025-21635: rds: sysctl: rds_tcp_{rcv,snd}buf: avoid using current->nsproxy

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-01-19 · updated 2026-10-30
Weakness: CWE-476

Description

In the Linux kernel, the following vulnerability has been resolved: rds: sysctl: rds_tcp_{rcv,snd}buf: avoid using current->nsproxy As mentioned in a previous commit of this series, using the 'net' structure via 'current' is not recommended for different reasons: - Inconsistency: getting info from the reader's/writer's netns vs only from the opener's netns. - current->nsproxy can be NULL in some cases, resulting in an 'Oops' (null-ptr-deref), e.g. when the current task is exiting, as spotted by syzbot [1] using acct(2). The per-netns structure can be obtained from the table->data using container_of(), then the 'net' one can be retrieved from the listen socket (if available).

Affected products

Linux kernel: from 4.6 before 6.12.10; 6.13-rc1, 6.13-rc2, 6.13-rc3, 6.13-rc4, 6.13-rc5, 6.13-rc6 — fixed in 6.12.10
Linux: 4.6 — fixed in 6.13

How to fix

Upgrade to a fixed version: Linux kernel 6.12.10; Linux 6.13. Check the vendor advisory for mitigations.

References

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