CVE-2026-74740 (GCVE-0-2026-74740)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:36 – Updated: 2026-08-26 14:36
VLAI
Title
net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_api: fix TOCTOU NULL deref on a->goto_chain tcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking rcu_access_pointer(a->goto_chain) and then calling tcf_action_goto_chain_exec(), which does a second, independent rcu_dereference_bh(a->goto_chain) read and immediately dereferences chain->filter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact replace path) can clear a->goto_chain between the two reads, so the second read returns NULL and tcf_action_goto_chain_exec() dereferences NULL. Fix the race by doing a single rcu_dereference_bh() read of a->goto_chain in tcf_action_exec(), checking it once for NULL, and passing the resulting chain pointer into tcf_action_goto_chain_exec(). This turns the split check/use into a single check/use on one value.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 , < 91d55fd1fdb85c8371ca8793c788ea7d5192383a (git)
Affected: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 , < 1ec48b6715c29b20105e3485206602cff6c51ae5 (git)
Affected: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 , < abceabc4408fca6a9dd52611f5d197dec9390d63 (git)
Affected: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 , < 6b70886ebc428eed43a069c8944a931b5fb3f4e4 (git)
Affected: ee3bbfe806cdb46b02cda63626cb50a7a7b19fc5 , < f60b396ee174206fe08ebf997d16cd3801b77b22 (git)
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Linux Linux Affected: 5.1
Unaffected: 0 , < 5.1 (semver)
Unaffected: 6.6.153 , ≤ 6.6.* (semver)
Unaffected: 6.12.105 , ≤ 6.12.* (semver)
Unaffected: 6.18.46 , ≤ 6.18.* (semver)
Unaffected: 7.1.10 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/act_api.c"
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      "cpeApplicability": [
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          "nodes": [
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              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_api: fix TOCTOU NULL deref on a-\u003egoto_chain\n\ntcf_action_exec() handles TC_ACT_GOTO_CHAIN by first checking\nrcu_access_pointer(a-\u003egoto_chain) and then calling\ntcf_action_goto_chain_exec(), which does a second, independent\nrcu_dereference_bh(a-\u003egoto_chain) read and immediately dereferences\nchain-\u003efilter_chain. A concurrent tcf_action_set_ctrlact() (e.g. the gact\nreplace path) can clear a-\u003egoto_chain between the two reads, so the second\nread returns NULL and tcf_action_goto_chain_exec() dereferences NULL.\n\nFix the race by doing a single rcu_dereference_bh() read of a-\u003egoto_chain\nin tcf_action_exec(), checking it once for NULL, and passing the resulting\nchain pointer into tcf_action_goto_chain_exec(). This turns the split\ncheck/use into a single check/use on one value."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-26T14:36:52.344Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/91d55fd1fdb85c8371ca8793c788ea7d5192383a"
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        },
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          "url": "https://git.kernel.org/stable/c/abceabc4408fca6a9dd52611f5d197dec9390d63"
        },
        {
          "url": "https://git.kernel.org/stable/c/6b70886ebc428eed43a069c8944a931b5fb3f4e4"
        },
        {
          "url": "https://git.kernel.org/stable/c/f60b396ee174206fe08ebf997d16cd3801b77b22"
        }
      ],
      "title": "net/sched: act_api: fix TOCTOU NULL deref on a-\u003egoto_chain",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74740",
    "datePublished": "2026-08-26T14:36:52.344Z",
    "dateReserved": "2026-08-15T05:44:03.930Z",
    "dateUpdated": "2026-08-26T14:36:52.344Z",
    "state": "PUBLISHED"
  },
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  "vulnerability-lookup:meta": {
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      "percentile": "0.07104"
    },
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-27T10:49:09+00:00",
      "cve": "CVE-2026-74740",
      "id": "CVE-2026-74740",
      "initial_release_date": "2026-08-26T00:00:00+00:00",
      "product_status:known_affected": "246",
      "product_status:known_not_affected": "28",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net/sched: act_api: fix TOCTOU NULL deref on a-\u003egoto_chain",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74740.json",
      "version": "3"
    }
  }
}



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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.

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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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