CVE-2026-43027 (GCVE-0-2026-43027)

Vulnerability from cvelistv5 – Published: 2026-05-01 14:15 – Updated: 2026-05-01 14:15
VLAI?
Title
netfilter: nf_conntrack_helper: pass helper to expect cleanup
Summary
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)
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: ac7b848390036dadd4351899d2a23748075916bd , < 5cf28d5c8dcbbe8af6d3b145babe491906d7bad1 (git)
Affected: ac7b848390036dadd4351899d2a23748075916bd , < 504ba4168466c91210c45acdc332479cfd5f2da6 (git)
Affected: ac7b848390036dadd4351899d2a23748075916bd , < dc1739eff48e34cc71d4e2f03715493fbcebd8af (git)
Affected: ac7b848390036dadd4351899d2a23748075916bd , < 2cf2737c85a2ba2b52024dafe68ffad2676f97be (git)
Affected: ac7b848390036dadd4351899d2a23748075916bd , < 2c16e4d64dd91227742dfe196a3e7b0568bef65a (git)
Affected: ac7b848390036dadd4351899d2a23748075916bd , < 620f3d14c1ef51d425060a3056ad8dbae8f998a3 (git)
Affected: ac7b848390036dadd4351899d2a23748075916bd , < 90bd7e8501349db3006d21fbc09df9ffcb172965 (git)
Affected: ac7b848390036dadd4351899d2a23748075916bd , < a242a9ae58aa46ff7dae51ce64150a93957abe65 (git)
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    Linux Linux Affected: 4.14
Unaffected: 0 , < 4.14 (semver)
Unaffected: 5.10.253 , ≤ 5.10.* (semver)
Unaffected: 5.15.203 , ≤ 5.15.* (semver)
Unaffected: 6.1.168 , ≤ 6.1.* (semver)
Unaffected: 6.6.134 , ≤ 6.6.* (semver)
Unaffected: 6.12.81 , ≤ 6.12.* (semver)
Unaffected: 6.18.22 , ≤ 6.18.* (semver)
Unaffected: 6.19.12 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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{
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          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_conntrack_helper.c"
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_helper: pass helper to expect cleanup\n\nnf_conntrack_helper_unregister() calls nf_ct_expect_iterate_destroy()\nto remove expectations belonging to the helper being unregistered.\nHowever, it passes NULL instead of the helper pointer as the data\nargument, so expect_iter_me() never matches any expectation and all\nof them survive the cleanup.\n\nAfter unregister returns, nfnl_cthelper_del() frees the helper\nobject immediately.  Subsequent expectation dumps or packet-driven\ninit_conntrack() calls then dereference the freed exp-\u003ehelper,\ncausing a use-after-free.\n\nPass the actual helper pointer so expectations referencing it are\nproperly destroyed before the helper object is freed.\n\n  BUG: KASAN: slab-use-after-free in string+0x38f/0x430\n  Read of size 1 at addr ffff888003b14d20 by task poc/103\n  Call Trace:\n   string+0x38f/0x430\n   vsnprintf+0x3cc/0x1170\n   seq_printf+0x17a/0x240\n   exp_seq_show+0x2e5/0x560\n   seq_read_iter+0x419/0x1280\n   proc_reg_read+0x1ac/0x270\n   vfs_read+0x179/0x930\n   ksys_read+0xef/0x1c0\n  Freed by task 103:\n  The buggy address is located 32 bytes inside of\n   freed 192-byte region [ffff888003b14d00, ffff888003b14dc0)"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-01T14:15:28.521Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
        {
          "url": "https://git.kernel.org/stable/c/a242a9ae58aa46ff7dae51ce64150a93957abe65"
        }
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    "datePublished": "2026-05-01T14:15:28.521Z",
    "dateReserved": "2026-05-01T14:12:55.976Z",
    "dateUpdated": "2026-05-01T14:15:28.521Z",
    "state": "PUBLISHED"
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  }
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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