{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-74660","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-08-15T05:44:03.924Z","datePublished":"2026-08-22T15:32:33.677Z","dateUpdated":"2026-08-25T05:41:14.285Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-25T05:41:14.285Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: ebt_nflog: pin the NFLOG backend\n\nnf_log_unregister() runs after the per-net teardown so its final RCU\ngrace period also drains readers that obtained the logger from a per-net\nbinding.  However, ebt_nflog passes an explicit ULOG log type to\nnf_log_packet() without holding a reference on the selected logger module,\nunlike the xt_NFLOG and nft_log frontends.\n\nAn ebtables nflog rule can therefore remain callable while nfnetlink_log\nis unloaded.  The resulting interleaving is:\n\n  CPU 0                               CPU 1\n  nfnetlink_log_fini()\n    unregister_pernet_subsys()\n      kfree(nfnl_log_pernet(net))\n                                      ebt_nflog_tg()\n                                        nf_log_packet()\n                                          nfulnl_log_packet()\n                                            instance_lookup_get_rcu()\n\nThe global ULOG logger is still registered at this point, so CPU 1\ndereferences the per-net state after CPU 0 has freed it.  KASAN reported:\n\n  BUG: KASAN: slab-use-after-free in instance_lookup_get_rcu\n  Read of size 8 at addr ff110001052e6210 by task poc/92\n  Call Trace:\n   instance_lookup_get_rcu+0x1ce/0x1f0 [nfnetlink_log]\n   nfulnl_log_packet+0x248/0x2fb0 [nfnetlink_log]\n   nf_log_packet+0x204/0x300\n   ebt_nflog_tg+0x351/0x550\n   ebt_do_table+0xedf/0x22b0\n  Allocated by task 90:\n   __kmalloc_noprof+0x186/0x470\n   ops_init+0x6d/0x420\n   register_pernet_operations+0x2f6/0x670\n   register_pernet_subsys+0x23/0x40\n  Freed by task 93:\n   kfree+0x131/0x3c0\n   ops_undo_list+0x3e3/0x700\n   unregister_pernet_operations+0x232/0x490\n   unregister_pernet_subsys+0x1c/0x30\n   nfnetlink_log_fini+0x34/0x450 [nfnetlink_log]\n\nAcquire the ULOG logger module reference when an ebt_nflog rule is\nvalidated and release it when the rule is destroyed.  Request the NFLOG\nbackend for legacy callers when needed, matching xt_NFLOG.  This prevents\nmodule teardown until all ebt_nflog rules have stopped using the logger."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The UAF is reached through ebtables setsockopt rule installation and nfnetlink_log module teardown (local administrative paths); per kernel CNA guidance, netfilter/ebtables bugs are scored Local even when bridge hook evaluation can be driven by forwarded frames.\nAC:L - The KASAN reproducer uses a deterministic two-thread race between nfnetlink_log_fini() module removal and concurrent bridge traffic through an active ebt_nflog rule; the attacker controls both the unload timing and packet generation without depending on uncontrollable victim state.\nPR:L - Installing an ebt_nflog rule requires CAP_NET_ADMIN in the socket network namespace, obtainable by unprivileged users via user+network namespaces (unshare -Urn); the documented PoC races module teardown concurrently with rule-driven traffic, matching standard CNA treatment for ebtables/netfilter paths.\nUI:N - No victim interaction is required beyond the attacker's own ebtables configuration, module unload coordination, and bridge traffic generation to hit the active nflog target during the teardown window.\nS:U - The slab use-after-free corrupts host kernel memory within the same security authority; this is not a VM escape, container breakout across an IOMMU boundary, or other cross-scope privilege transition.\nC:H - KASAN confirmed a slab use-after-free read in instance_lookup_get_rcu() against freed nfnl_log_pernet state; UAF on the per-net instance hash table enables attacker-influenced heap reads and disclosure of adjacent kernel memory contents.\nI:H - Use-after-free on the nfnl_log_pernet structure and nfulnl_instance objects provides standard heap grooming primitives; freed slab reuse can redirect subsequent logging operations into attacker-controlled data for arbitrary kernel writes or control-flow hijack.\nA:H - The UAF read on freed per-net logging state can immediately trigger a kernel BUG/oops (as reported by KASAN) and reliably causes denial of service; repeated bridge traffic during module teardown can panic the affected host."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/netfilter/ebt_nflog.c"],"versions":[{"version":"c83fa19603bdaeef17b815713dbbe3230c8a34ee","lessThan":"3bcce49d617c593c7606083bfdb464a1761fa68d","status":"affected","versionType":"git"},{"version":"c83fa19603bdaeef17b815713dbbe3230c8a34ee","lessThan":"394d7939c6b2b9e6bea0844c89efb5913168d898","status":"affected","versionType":"git"},{"version":"c83fa19603bdaeef17b815713dbbe3230c8a34ee","lessThan":"2cac4294f184c9bc19ff82552c62b80498694c39","status":"affected","versionType":"git"},{"version":"c83fa19603bdaeef17b815713dbbe3230c8a34ee","lessThan":"9d8a94b48b393885e7f876c8ef68ed4da5012078","status":"affected","versionType":"git"},{"version":"c83fa19603bdaeef17b815713dbbe3230c8a34ee","lessThan":"6809379a860b9fccbb5435bf08343f6d081ac68d","status":"affected","versionType":"git"},{"version":"c83fa19603bdaeef17b815713dbbe3230c8a34ee","lessThan":"47a119ec8a7e2d5c8c4e86fb1a56c4e696e500fb","status":"affected","versionType":"git"},{"version":"c83fa19603bdaeef17b815713dbbe3230c8a34ee","lessThan":"e2ab7e878bdbe80104c879c31fd2d82a476703b8","status":"affected","versionType":"git"},{"version":"c83fa19603bdaeef17b815713dbbe3230c8a34ee","lessThan":"30825970339c107bacaf7f61af90fcdb1f597ca1","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/bridge/netfilter/ebt_nflog.c"],"versions":[{"version":"4.12","status":"affected"},{"version":"0","lessThan":"4.12","status":"unaffected","versionType":"semver"},{"version":"5.10.265","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.216","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.183","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.152","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.104","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.45","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.1.9","lessThanOrEqual":"7.1.*","status":"unaffected","versionType":"semver"},{"version":"7.2","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"5.10.265"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"5.15.216"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.1.183"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.6.152"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.12.104"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"6.18.45"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"7.1.9"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.12","versionEndExcluding":"7.2"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/3bcce49d617c593c7606083bfdb464a1761fa68d"},{"url":"https://git.kernel.org/stable/c/394d7939c6b2b9e6bea0844c89efb5913168d898"},{"url":"https://git.kernel.org/stable/c/2cac4294f184c9bc19ff82552c62b80498694c39"},{"url":"https://git.kernel.org/stable/c/9d8a94b48b393885e7f876c8ef68ed4da5012078"},{"url":"https://git.kernel.org/stable/c/6809379a860b9fccbb5435bf08343f6d081ac68d"},{"url":"https://git.kernel.org/stable/c/47a119ec8a7e2d5c8c4e86fb1a56c4e696e500fb"},{"url":"https://git.kernel.org/stable/c/e2ab7e878bdbe80104c879c31fd2d82a476703b8"},{"url":"https://git.kernel.org/stable/c/30825970339c107bacaf7f61af90fcdb1f597ca1"}],"title":"netfilter: ebt_nflog: pin the NFLOG backend","x_generator":{"engine":"bippy-1.2.0"}}}}