CVE-2024-41042: netfilter: nf_tables: prefer nft_chain_validate

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: 2024-07-29 · updated 2026-06-17
Weakness: CWE-787

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: prefer nft_chain_validate nft_chain_validate already performs loop detection because a cycle will result in a call stack overflow (ctx->level >= NFT_JUMP_STACK_SIZE). It also follows maps via ->validate callback in nft_lookup, so there appears no reason to iterate the maps again. nf_tables_check_loops() and all its helper functions can be removed. This improves ruleset load time significantly, from 23s down to 12s. This also fixes a crash bug. Old loop detection code can result in unbounded recursion: BUG: TASK stack guard page was hit at .... Oops: stack guard page: 0000 [#1] PREEMPT SMP KASAN CPU: 4 PID: 1539 Comm: nft Not tainted 6.10.0-rc5+ #1 [..] with a suitable ruleset during validation of register stores. I can't see any actual reason to attempt to check for this from nft_validate_register_store(), at this point the transaction is still in progress, so we don't have a full picture of the rule graph. For nf-next it might make sense to either remove it or make this depend on table->validate_state in case we could catch an error earlier (for improved error reporting to userspace).

Affected products

Linux kernel: from 3.13 before 4.19.320; from 4.20 before 5.4.282; from 5.5 before 5.10.224; from 5.11 before 5.15.165; from 5.16 before 6.1.105; from 6.2 before 6.6.46 — fixed in 4.19.320, 5.10.224, 5.15.165, 5.4.282, 6.1.105, 6.6.46

How to fix

Upgrade to a fixed version: Linux kernel 4.19.320, 5.10.224, 5.15.165, 5.4.282. Check the vendor advisory for mitigations.

References

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