FKIE_CVE-2026-86805

Vulnerability from fkie_nvd - Published: 2026-09-22 16:18 - Updated: 2026-09-23 04:17
Severity
6.3 (Medium) - CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L
Summary
A time-of-check to time-of-use (TOCTOU) race condition in the dynamic loader (ld.so) of the GNU C Library (glibc) versions 2.14 through 2.44 allows a local attacker to escalate privileges. When expanding $ORIGIN in DT_RPATH for setuid/setgid (AT_SECURE) programs, glibc validates the lexically normalized search path against the trusted directories but then opens the raw, un-normalized path. On systems where the Linux fs.protected_hardlinks sysctl is disabled, a local attacker who hard-links such a program into an attacker-controlled directory and wins a race to replace an intermediate path component with a symbolic link can direct the loader outside the trusted directory, causing it to load an attacker-controlled shared object and execute arbitrary code with the elevated privileges of the program. Exploitation requires an installed setuid or setgid binary whose DT_RPATH uses $ORIGIN followed by ".." traversal that normalizes into a trusted directory, and the ability to hard-link that binary and win the race by swapping a path component for a symbolic link. Major Linux-based OS distributions ship with fs.protected_hardlinks enabled by default and mitigate the vulnerability.
References
3ff69d7a-14f2-4f67-a097-88dee7810d18https://sourceware.org/bugzilla/show_bug.cgi?id=34360
3ff69d7a-14f2-4f67-a097-88dee7810d18https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0022
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "glibc",
          "vendor": "The GNU C Library",
          "versions": [
            {
              "lessThan": "2.45",
              "status": "affected",
              "version": "2.14",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A time-of-check to time-of-use (TOCTOU) race condition in the dynamic loader (ld.so) of the GNU C Library (glibc) versions 2.14 through 2.44 allows a local attacker to escalate privileges. When expanding $ORIGIN in DT_RPATH for setuid/setgid (AT_SECURE) programs, glibc validates the lexically normalized search path against the trusted directories but then opens the raw, un-normalized path. On systems where the Linux fs.protected_hardlinks sysctl is disabled, a local attacker who hard-links such a program into an attacker-controlled directory and wins a race to replace an intermediate path component with a symbolic link can direct the loader outside the trusted directory, causing it to load an attacker-controlled shared object and execute arbitrary code with the elevated privileges of the program.\n\nExploitation requires an installed setuid or setgid binary whose DT_RPATH uses $ORIGIN followed by \"..\" traversal that normalizes into a trusted directory, and the ability to hard-link that binary and win the race by swapping a path component for a symbolic link. Major Linux-based OS distributions ship with fs.protected_hardlinks enabled by default and mitigate the vulnerability."
    }
  ],
  "id": "CVE-2026-86805",
  "lastModified": "2026-09-23T04:17:57.137",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "LOCAL",
          "availabilityImpact": "LOW",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:L",
          "version": "3.1"
        },
        "exploitabilityScore": 0.8,
        "impactScore": 5.5,
        "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-86805",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-22T00:00:00+00:00",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-22T16:18:06.230",
  "references": [
    {
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
      "url": "https://sourceware.org/bugzilla/show_bug.cgi?id=34360"
    },
    {
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
      "url": "https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0022"
    }
  ],
  "sourceIdentifier": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-367"
        }
      ],
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
      "type": "Secondary"
    }
  ]
}



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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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