FKIE_CVE-2026-8674

Vulnerability from fkie_nvd - Published: 2026-09-17 17:16 - Updated: 2026-09-17 19:17
Severity
5.3 (Medium) - CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Summary
Initializing the DNS stub resolver from an /etc/resolv.conf file, or a LOCALDOMAIN environment variable, whose search list contains a domain of roughly 200 characters or more in the GNU C Library version 2.26 to 2.44 results in an assertion failure which aborts the process. The resolver truncates the search list when copying it into the fixed-size _res.defdname buffer, then asserts that the copy is consistent with the full configuration. The consistency check compared against the wrong size and did not handle a first entry that does not fit, so a correctly truncated list failed the assertion. Any process that resolves names through the library is affected, including long-running processes that reload /etc/resolv.conf on the next query after it changes. Search domains are commonly written to /etc/resolv.conf from data received over DHCP or from a VPN server, so an attacker on the local network may be able to trigger this without privileges on the target system, subject to validation by the network configuration software.
References
3ff69d7a-14f2-4f67-a097-88dee7810d18https://joshua.hu/fuzzing-glibc-libresolv
3ff69d7a-14f2-4f67-a097-88dee7810d18https://sourceware.org/bugzilla/show_bug.cgi?id=31026
3ff69d7a-14f2-4f67-a097-88dee7810d18https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0021
3ff69d7a-14f2-4f67-a097-88dee7810d18https://sourceware.org/git/?p=glibc.git;a=commit;h=506ea57086bfb9ce3daff1c14246a1cb532aba0a
af854a3a-2127-422b-91ae-364da2661108http://www.openwall.com/lists/oss-security/2026/09/17/4
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "glibc",
          "vendor": "The GNU C Library",
          "versions": [
            {
              "lessThanOrEqual": "2.44",
              "status": "affected",
              "version": "2.26",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Initializing the DNS stub resolver from an /etc/resolv.conf file, or a LOCALDOMAIN environment variable, whose search list contains a domain of roughly 200 characters or more in the GNU C Library version 2.26 to 2.44 results in an assertion failure which aborts the process.\n\nThe resolver truncates the search list when copying it into the fixed-size _res.defdname buffer, then asserts that the copy is consistent with the full configuration.  The consistency check compared against the wrong size and did not handle a first entry that does not fit, so a correctly truncated list failed the assertion.  Any process that resolves names through the library is affected, including long-running processes that reload /etc/resolv.conf on the next query after it changes.  Search domains are commonly written to /etc/resolv.conf from data received over DHCP or from a VPN server, so an attacker on the local network may be able to trigger this without privileges on the target system, subject to validation by the network configuration software."
    }
  ],
  "id": "CVE-2026-8674",
  "lastModified": "2026-09-17T19:17:06.427",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "HIGH",
          "attackVector": "ADJACENT_NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 5.3,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.6,
        "impactScore": 3.6,
        "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-8674",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-09-17T18:05:54.714741Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-09-17T17:16:53.220",
  "references": [
    {
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
      "url": "https://joshua.hu/fuzzing-glibc-libresolv"
    },
    {
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
      "url": "https://sourceware.org/bugzilla/show_bug.cgi?id=31026"
    },
    {
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
      "url": "https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0021"
    },
    {
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
      "url": "https://sourceware.org/git/?p=glibc.git;a=commit;h=506ea57086bfb9ce3daff1c14246a1cb532aba0a"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
      "url": "http://www.openwall.com/lists/oss-security/2026/09/17/4"
    }
  ],
  "sourceIdentifier": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-617"
        }
      ],
      "source": "3ff69d7a-14f2-4f67-a097-88dee7810d18",
      "type": "Secondary"
    }
  ]
}



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