CVE-2022-49110: netfilter: conntrack: revisit gc autotuning

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-02-26 · updated 2026-10-15

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: conntrack: revisit gc autotuning as of commit 4608fdfc07e1 ("netfilter: conntrack: collect all entries in one cycle") conntrack gc was changed to run every 2 minutes. On systems where conntrack hash table is set to large value, most evictions happen from gc worker rather than the packet path due to hash table distribution. This causes netlink event overflows when events are collected. This change collects average expiry of scanned entries and reschedules to the average remaining value, within 1 to 60 second interval. To avoid event overflows, reschedule after each bucket and add a limit for both run time and number of evictions per run. If more entries have to be evicted, reschedule and restart 1 jiffy into the future.

Affected products

Linux kernel: before 5.15.34; from 5.16 before 5.16.20; from 5.17 before 5.17.3 — fixed in 5.15.34, 5.16.20, 5.17.3

How to fix

Upgrade to a fixed version: Linux kernel 5.15.34, 5.16.20, 5.17.3. Check the vendor advisory for mitigations.

References

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