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CVE PROGRAM SOURCE RECORDUnscored

CVE-2026-43027

netfilter: nf_conntrack_helper: pass helper to expect cleanup

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_helper: pass helper to expect cleanup nf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy() to remove expectations belonging to the helper being unregistered. However, it passes NULL instead of the helper pointer as the data argument, so expect_iter_me() never matches any expectation and all of them survive the cleanup. After unregister returns, nfnl_cthelper_del() frees the helper object immediately. Subsequent expectation dumps or packet-driven init_conntrack() calls then dereference the freed exp->helper, causing a use-after-free. Pass the actual helper pointer so expectations referencing it are properly destroyed before the helper object is freed. BUG: KASAN: slab-use-after-free in string+0x38f/0x430 Read of size 1 at addr ffff888003b14d20 by task poc/103 Call Trace: string+0x38f/0x430 vsnprintf+0x3cc/0x1170 seq_printf+0x17a/0x240 exp_seq_show+0x2e5/0x560 seq_read_iter+0x419/0x1280 proc_reg_read+0x1ac/0x270 vfs_read+0x179/0x930 ksys_read+0xef/0x1c0 Freed by task 103: The buggy address is located 32 bytes inside of freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • ac7b848390036dadd4351899d2a23748075916bd to < 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1affected
  • ac7b848390036dadd4351899d2a23748075916bd to < 504ba4168466c91210c45acdc332479cfd5f2da6affected
  • ac7b848390036dadd4351899d2a23748075916bd to < dc1739eff48e34cc71d4e2f03715493fbcebd8afaffected
  • ac7b848390036dadd4351899d2a23748075916bd to < 2cf2737c85a2ba2b52024dafe68ffad2676f97beaffected
  • ac7b848390036dadd4351899d2a23748075916bd to < 2c16e4d64dd91227742dfe196a3e7b0568bef65aaffected
  • ac7b848390036dadd4351899d2a23748075916bd to < 620f3d14c1ef51d425060a3056ad8dbae8f998a3affected
  • ac7b848390036dadd4351899d2a23748075916bd to < 90bd7e8501349db3006d21fbc09df9ffcb172965affected
  • ac7b848390036dadd4351899d2a23748075916bd to < a242a9ae58aa46ff7dae51ce64150a93957abe65affected

Linux Linux

Default version status: affected

  • 4.14affected
  • 0 to < 4.14unaffected
  • 5.10.253 to ≤ 5.10.*unaffected
  • 5.15.203 to ≤ 5.15.*unaffected
  • 6.1.168 to ≤ 6.1.*unaffected
  • 6.6.134 to ≤ 6.6.*unaffected
  • 6.12.81 to ≤ 6.12.*unaffected
  • 6.18.22 to ≤ 6.18.*unaffected
  • 6.19.12 to ≤ 6.19.*unaffected
  • 7.0 to ≤ *unaffected

References