CVE-2022-49698: netfilter: use get_random_u32 instead of prandom

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: 2025-02-26 · updated 2026-06-17

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: use get_random_u32 instead of prandom bh might occur while updating per-cpu rnd_state from user context, ie. local_out path. BUG: using smp_processor_id() in preemptible [00000000] code: nginx/2725 caller is nft_ng_random_eval+0x24/0x54 [nft_numgen] Call Trace: check_preemption_disabled+0xde/0xe0 nft_ng_random_eval+0x24/0x54 [nft_numgen] Use the random driver instead, this also avoids need for local prandom state. Moreover, prandom now uses the random driver since d4150779e60f ("random32: use real rng for non-deterministic randomness"). Based on earlier patch from Pablo Neira.

Affected products

Linux kernel: from 4.18 before 5.10.127; from 5.11 before 5.15.51; from 5.16 before 5.18.8; 5.19-rc1, 5.19-rc2, 5.19-rc3 — fixed in 5.10.127, 5.15.51, 5.18.8

How to fix

Upgrade to a fixed version: Linux kernel 5.10.127, 5.15.51, 5.18.8. Check the vendor advisory for mitigations.

References

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