CVE-2024-26739: net/sched: act_mirred: don't override retval if we already lost the skb

Severity: high (CVSS 7.8 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: 2024-04-03 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_mirred: don't override retval if we already lost the skb If we're redirecting the skb, and haven't called tcf_mirred_forward(), yet, we need to tell the core to drop the skb by setting the retcode to SHOT. If we have called tcf_mirred_forward(), however, the skb is out of our hands and returning SHOT will lead to UaF. Move the retval override to the error path which actually need it.

Affected products

Debian Linux: 11.0
Linux kernel: from 4.19 before 5.10.238; from 5.11 before 5.15.182; from 5.16 before 6.1.136; from 6.2 before 6.6.19; from 6.7 before 6.7.7; 6.8-rc1, 6.8-rc2, 6.8-rc3, 6.8-rc4 — fixed in 5.10.238, 5.15.182, 6.1.136, 6.6.19, 6.7.7

How to fix

Upgrade to a fixed version: Linux kernel 5.10.238, 5.15.182, 6.1.136, 6.6.19. Check the vendor advisory for mitigations.

References

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