CVE-2026-97985 (GCVE-0-2026-97985)

Vulnerability from cvelistv5 – Published: 2026-09-25 10:23 – Updated: 2026-09-25 10:23
VLAI
Title
af_unix: Update last skb marker in manage_oob().
Summary
In the Linux kernel, the following vulnerability has been resolved: af_unix: Update last skb marker in manage_oob(). Fahad Alharbi reported that blocking recv(MSG_PEEK) could hog CPU due to OOB skb. In the following cases, manage_oob() skips OOB skb(s) and returns NULL for the last recv(MSG_PEEK): socketpair(AF_UNIX, SOCK_STREAM, 0, sk); 1) skb -> OOB skb -> NULL send(sk[0], "ab", 2, MSG_OOB); recv(sk[1], buf, 0, MSG_PEEK); 2) skb -> consumed OOB skb -> NULL send(sk[0], "ab", 2, MSG_OOB); recv(sk[1], buf, 1, MSG_OOB); recv(sk[1], buf, 0, MSG_PEEK); 3) consumed OOB skb -> OOB skb -> NULL send(sk[0], "a", 1, MSG_OOB); recv(sk[1], buf, 0, MSG_OOB); send(sk[0], "b", 1, MSG_OOB); recv(sk[1], buf, 1, MSG_PEEK); Then, @copied is 0 in unix_stream_read_generic() (zero-length buffer, or non-OOB skb is not yet consumed), and unix_stream_data_wait() is called. However, it returns immediately because @last is not updated in unix_stream_read_generic(), and the thread busy-waits for a new skb. Let's update @last in manage_oob(). For MSG_PEEK, @last is updated with the skipped OOB, and for the non-peek case, @last matches the returned value (when !copied) because OOB is unlinked. Note that manage_oob() is inlined and no stack canary is added.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 22dd70eb2c3d754862964377a75abafd3167346b , < 0630bfc773d85ac44da05b2c5a037dbbd39301ab (git)
Affected: 22dd70eb2c3d754862964377a75abafd3167346b , < f1816b3d7ce80dcf086bb68ff5ae6e09520ca1fa (git)
Affected: 22dd70eb2c3d754862964377a75abafd3167346b , < fc62a26493a98a0424d9dae2eb92a1daa1321f65 (git)
Affected: 22dd70eb2c3d754862964377a75abafd3167346b , < 94fd4debd2e3a69cf93e766c8b328a810c228119 (git)
Affected: ae3f9e1221b31b18dbd4c4b85d08574996bbd973 (git)
Affected: ba0db4638525b8b054b3d546b45f7e473f477027 (git)
Affected: 022d81a709cd553bbe2db8675f8e824f4aee6284 (git)
Affected: 16dc252e7007547a7b72a2c21022ef81fb45e6a3 (git)
Affected: 5.15.157 , < 5.16 (semver)
Affected: 6.1.88 , < 6.2 (semver)
Affected: 6.6.29 , < 6.7 (semver)
Affected: 6.8.8 , < 6.9 (semver)
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Linux Linux Affected: 6.9
Unaffected: 0 , < 6.9 (semver)
Unaffected: 6.12.111 , ≤ 6.12.* (semver)
Unaffected: 6.18.53 , ≤ 6.18.* (semver)
Unaffected: 7.2.7 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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{
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Update last skb marker in manage_oob().\n\nFahad Alharbi reported that blocking recv(MSG_PEEK) could hog CPU\ndue to OOB skb.\n\nIn the following cases, manage_oob() skips OOB skb(s) and returns\nNULL for the last recv(MSG_PEEK):\n\n  socketpair(AF_UNIX, SOCK_STREAM, 0, sk);\n\n  1) skb -\u003e OOB skb -\u003e NULL\n     send(sk[0], \"ab\", 2, MSG_OOB);\n     recv(sk[1], buf, 0, MSG_PEEK);\n\n  2) skb -\u003e consumed OOB skb -\u003e NULL\n     send(sk[0], \"ab\", 2, MSG_OOB);\n     recv(sk[1], buf, 1, MSG_OOB);\n     recv(sk[1], buf, 0, MSG_PEEK);\n\n  3) consumed OOB skb -\u003e OOB skb -\u003e NULL\n     send(sk[0], \"a\", 1, MSG_OOB);\n     recv(sk[1], buf, 0, MSG_OOB);\n     send(sk[0], \"b\", 1, MSG_OOB);\n     recv(sk[1], buf, 1, MSG_PEEK);\n\nThen, @copied is 0 in unix_stream_read_generic() (zero-length buffer,\nor non-OOB skb is not yet consumed), and unix_stream_data_wait() is\ncalled.\n\nHowever, it returns immediately because @last is not updated in\nunix_stream_read_generic(), and the thread busy-waits for a new skb.\n\nLet\u0027s update @last in manage_oob().\n\nFor MSG_PEEK, @last is updated with the skipped OOB, and for the\nnon-peek case, @last matches the returned value (when !copied)\nbecause OOB is unlinked.\n\nNote that manage_oob() is inlined and no stack canary is added."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-25T10:23:20.173Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        },
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-97985",
    "datePublished": "2026-09-25T10:23:20.173Z",
    "dateReserved": "2026-09-25T10:18:58.208Z",
    "dateUpdated": "2026-09-25T10:23:20.173Z",
    "state": "PUBLISHED"
  },
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\naf_unix: Update last skb marker in manage_oob().\n\nFahad Alharbi reported that blocking recv(MSG_PEEK) could hog CPU\ndue to OOB skb.\n\nIn the following cases, manage_oob() skips OOB skb(s) and returns\nNULL for the last recv(MSG_PEEK):\n\n  socketpair(AF_UNIX, SOCK_STREAM, 0, sk);\n\n  1) skb -\u003e OOB skb -\u003e NULL\n     send(sk[0], \"ab\", 2, MSG_OOB);\n     recv(sk[1], buf, 0, MSG_PEEK);\n\n  2) skb -\u003e consumed OOB skb -\u003e NULL\n     send(sk[0], \"ab\", 2, MSG_OOB);\n     recv(sk[1], buf, 1, MSG_OOB);\n     recv(sk[1], buf, 0, MSG_PEEK);\n\n  3) consumed OOB skb -\u003e OOB skb -\u003e NULL\n     send(sk[0], \"a\", 1, MSG_OOB);\n     recv(sk[1], buf, 0, MSG_OOB);\n     send(sk[0], \"b\", 1, MSG_OOB);\n     recv(sk[1], buf, 1, MSG_PEEK);\n\nThen, @copied is 0 in unix_stream_read_generic() (zero-length buffer,\nor non-OOB skb is not yet consumed), and unix_stream_data_wait() is\ncalled.\n\nHowever, it returns immediately because @last is not updated in\nunix_stream_read_generic(), and the thread busy-waits for a new skb.\n\nLet\u0027s update @last in manage_oob().\n\nFor MSG_PEEK, @last is updated with the skipped OOB, and for the\nnon-peek case, @last matches the returned value (when !copied)\nbecause OOB is unlinked.\n\nNote that manage_oob() is inlined and no stack canary is added."
          }
        ],
        "id": "CVE-2026-97985",
        "lastModified": "2026-09-25T11:17:26.560",
        "metrics": {},
        "published": "2026-09-25T11:17:26.560",
        "references": [
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    }
  }
}



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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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