FKIE_CVE-2026-27456

Vulnerability from fkie_nvd - Published: 2026-04-03 22:16 - Updated: 2026-04-22 16:08
Severity ?
4.7 (Medium) - CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Summary
util-linux is a random collection of Linux utilities. Prior to version 2.41.4, a TOCTOU (Time-of-Check-Time-of-Use) vulnerability has been identified in the SUID binary /usr/bin/mount from util-linux. The mount binary, when setting up loop devices, validates the source file path with user privileges via fork() + setuid() + realpath(), but subsequently re-canonicalizes and opens it with root privileges (euid=0) without verifying that the path has not been replaced between both operations. Neither O_NOFOLLOW, nor inode comparison, nor post-open fstat() are employed. This allows a local unprivileged user to replace the source file with a symlink pointing to any root-owned file or device during the race window, causing the SUID binary to open and mount it as root. Exploitation requires an /etc/fstab entry with user,loop options whose path points to a directory where the attacker has write permission, and that /usr/bin/mount has the SUID bit set (the default configuration on virtually all Linux distributions). The impact is unauthorized read access to root-protected files and block devices, including backup images, disk volumes, and any file containing a valid filesystem. This issue has been patched in version 2.41.4.
References
security-advisories@github.comhttps://github.com/util-linux/util-linux/commit/5e390467b26a3cf3fecc04e1a0d482dff3162fc4Patch
security-advisories@github.comhttps://github.com/util-linux/util-linux/releases/tag/v2.41.4Product
security-advisories@github.comhttps://github.com/util-linux/util-linux/security/advisories/GHSA-qq4x-vfq4-9h9gExploit, Vendor Advisory
134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/util-linux/util-linux/security/advisories/GHSA-qq4x-vfq4-9h9gExploit, Vendor Advisory
Impacted products
Vendor Product Version
kernel util-linux *
To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:a:kernel:util-linux:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "A0F464C1-2AC1-4B59-B522-89DD9D072C7F",
              "versionEndExcluding": "2.41.4",
              "vulnerable": true
            }
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          "negate": false,
          "operator": "OR"
        }
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  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "util-linux is a random collection of Linux utilities. Prior to version 2.41.4, a TOCTOU (Time-of-Check-Time-of-Use) vulnerability has been identified in the SUID binary /usr/bin/mount from util-linux. The mount binary, when setting up loop devices, validates the source file path with user privileges via fork() + setuid() + realpath(), but subsequently re-canonicalizes and opens it with root privileges (euid=0) without verifying that the path has not been replaced between both operations. Neither O_NOFOLLOW, nor inode comparison, nor post-open fstat() are employed. This allows a local unprivileged user to replace the source file with a symlink pointing to any root-owned file or device during the race window, causing the SUID binary to open and mount it as root. Exploitation requires an /etc/fstab entry with user,loop options whose path points to a directory where the attacker has write permission, and that /usr/bin/mount has the SUID bit set (the default configuration on virtually all Linux distributions). The impact is unauthorized read access to root-protected files and block devices, including backup images, disk volumes, and any file containing a valid filesystem. This issue has been patched in version 2.41.4."
    }
  ],
  "id": "CVE-2026-27456",
  "lastModified": "2026-04-22T16:08:55.100",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "LOCAL",
          "availabilityImpact": "NONE",
          "baseScore": 4.7,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N",
          "version": "3.1"
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        "impactScore": 3.6,
        "source": "security-advisories@github.com",
        "type": "Secondary"
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  },
  "published": "2026-04-03T22:16:25.400",
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    },
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      "tags": [
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    },
    {
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      "tags": [
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      "url": "https://github.com/util-linux/util-linux/security/advisories/GHSA-qq4x-vfq4-9h9g"
    },
    {
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  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-59"
        },
        {
          "lang": "en",
          "value": "CWE-269"
        },
        {
          "lang": "en",
          "value": "CWE-367"
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      "source": "security-advisories@github.com",
      "type": "Secondary"
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    {
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          "value": "CWE-367"
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      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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