CVE-2026-99181 (GCVE-0-2026-99181)
Vulnerability from cvelistv5
Published
2026-10-28 10:35
Modified
2026-10-28 10:35
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: autofs: ignore notification errors from a replaced pipe autofs_notify_daemon() takes a reference to the current notification pipe under wq_mutex, then drops the mutex before writing the request. The write can block while the daemon enters catatonic mode and installs a replacement pipe. If the old pipe's reader is then closed, the delayed write returns -EPIPE and the generic error path enters catatonic mode again. That transition acts on the current superblock state, closes the replacement pipe, and releases the new daemon generation's wait queues. Only enter catatonic mode when the pipe which failed is still the current pipe. Factor the already-locked transition so the identity check and state change are atomic with respect to another replacement. This was reproduced on v7.3-rc5-337-gff47652a4b66c in a local QEMU guest. An unprivileged UID 65534 lookup filled the old packet pipe before a normal CATATONIC/SETPIPEFD restart. On the unmodified kernel, the new pipe received HUP and both a pending victim lookup and a later lookup failed with ENOENT in two out of two fresh-mount runs. With this change, the new pipe remained active, received an intact 304-byte request, and both victim lookups completed in two out of two runs. Normal lookup and restart-without-a-blocked-writer controls passed. No KASAN, oops, refcount, or lock diagnostic was observed. A source reproducer and complete local logs are available privately on request. The demonstrated impact is limited to denial of a shared autofs service during a legitimate daemon restart. No memory corruption, information leak, privilege escalation, or code execution primitive was observed.
References
Impacted products
Vendor Product Version
Linux Linux Version: 8d7b48e0bc5fa01a818eac713d4cb0763090cd0e
Version: 8d7b48e0bc5fa01a818eac713d4cb0763090cd0e
Version: 8d7b48e0bc5fa01a818eac713d4cb0763090cd0e
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/autofs/waitq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "1a177064f501ed4b67873a43aae5d5bdb18b3704",
              "status": "affected",
              "version": "8d7b48e0bc5fa01a818eac713d4cb0763090cd0e",
              "versionType": "git"
            },
            {
              "lessThan": "fb296391f685d82dbb93621a970fb234cea45280",
              "status": "affected",
              "version": "8d7b48e0bc5fa01a818eac713d4cb0763090cd0e",
              "versionType": "git"
            },
            {
              "lessThan": "65676cd4203c0e41a94caf54080a7f0a95434bda",
              "status": "affected",
              "version": "8d7b48e0bc5fa01a818eac713d4cb0763090cd0e",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "fs/autofs/waitq.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "2.6.28"
            },
            {
              "lessThan": "2.6.28",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.59",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.59",
                  "versionStartIncluding": "2.6.28",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.13",
                  "versionStartIncluding": "2.6.28",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.3",
                  "versionStartIncluding": "2.6.28",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nautofs: ignore notification errors from a replaced pipe\n\nautofs_notify_daemon() takes a reference to the current notification\npipe under wq_mutex, then drops the mutex before writing the request. The\nwrite can block while the daemon enters catatonic mode and installs a\nreplacement pipe.\n\nIf the old pipe\u0027s reader is then closed, the delayed write returns -EPIPE\nand the generic error path enters catatonic mode again. That transition\nacts on the current superblock state, closes the replacement pipe, and\nreleases the new daemon generation\u0027s wait queues.\n\nOnly enter catatonic mode when the pipe which failed is still the current\npipe. Factor the already-locked transition so the identity check and state\nchange are atomic with respect to another replacement.\n\nThis was reproduced on v7.3-rc5-337-gff47652a4b66c in a local QEMU guest.\nAn unprivileged UID 65534 lookup filled the old packet pipe before a\nnormal CATATONIC/SETPIPEFD restart. On the unmodified kernel, the new pipe\nreceived HUP and both a pending victim lookup and a later lookup failed\nwith ENOENT in two out of two fresh-mount runs.\n\nWith this change, the new pipe remained active, received an intact\n304-byte request, and both victim lookups completed in two out of two\nruns. Normal lookup and restart-without-a-blocked-writer controls passed.\nNo KASAN, oops, refcount, or lock diagnostic was observed. A source\nreproducer and complete local logs are available privately on request.\n\nThe demonstrated impact is limited to denial of a shared autofs service\nduring a legitimate daemon restart. No memory corruption, information leak,\nprivilege escalation, or code execution primitive was observed."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-28T10:35:34.443Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/1a177064f501ed4b67873a43aae5d5bdb18b3704"
        },
        {
          "url": "https://git.kernel.org/stable/c/fb296391f685d82dbb93621a970fb234cea45280"
        },
        {
          "url": "https://git.kernel.org/stable/c/65676cd4203c0e41a94caf54080a7f0a95434bda"
        }
      ],
      "title": "autofs: ignore notification errors from a replaced pipe",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-99181",
    "datePublished": "2026-10-28T10:35:34.443Z",
    "dateReserved": "2026-09-25T10:25:14.399Z",
    "dateUpdated": "2026-10-28T10:35:34.443Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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