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CVE-2026-74660

netfilter: ebt_nflog: pin the NFLOG backend

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.265, 5.15.216, 6.1.183, 6.6.152, 6.12.104, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: total

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: total

  3. Record last updated

Affected versions

  • Linux 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 Linux

    4.12

  • KernelLinux

    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

References 8

git.kernel.org