Assertion failure in the DNS stub resolver with a long search domain

{
  "id": "80a860fe8b2506231e10ba2f2f752e36bb21fd45bfadcb2d0e69c48ae05dc9f0",
  "url": "https://osv.dev/vulnerability/CVE-2026-8674",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Assertion failure in the DNS stub resolver with a long search domain",
    "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.",
    "evidence": "osv:CVE-2026-8674",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-8674",
      "aliases": [
        "CVE-2026-8674"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://sourceware.org/git/glibc.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "1c9a5c270d8b66f30dcfaf1cb2d6cf39d3e18369"
                },
                {
                  "last_affected": "c3a3a9808ad3ab4a3336836833f83288b672ccbf"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "introduced": "2.26"
                      },
                      {
                        "last_affected": "2.44"
                      }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "StandardRange"
                  }
                ]
              }
            }
          ],
          "versions": [
            "glibc-2.44",
            "glibc-2.43.9000",
            "glibc-2.43",
            "glibc-2.42",
            "glibc-2.42.9000",
            "glibc-2.41.9000",
            "glibc-2.41",
            "glibc-2.40",
            "glibc-2.40.9000",
            "glibc-2.39.9000",
            "glibc-2.39",
            "glibc-2.38",
            "glibc-2.38.9000",
            "glibc-2.37",
            "glibc-2.37.9000",
            "glibc-2.36",
            "glibc-2.36.9000",
            "glibc-2.35",
            "glibc-2.35.9000",
            "glibc-2.34",
            "glibc-2.34.9000",
            "glibc-2.33",
            "glibc-2.33.9000",
            "glibc-2.32",
            "glibc-2.32.9000",
            "glibc-2.31",
            "glibc-2.31.9000",
            "changelog-ends-here",
            "glibc-2.30",
            "glibc-2.30.9000",
            "glibc-2.29",
            "glibc-2.29.9000",
            "glibc-2.28",
            "glibc-2.28.9000",
            "glibc-2.27",
            "glibc-2.27.9000",
            "glibc-2.26",
            "glibc-2.26.9000"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-8674.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:37.010203525Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/8xxx/CVE-2026-8674.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-8674",
        "https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0021",
        "https://sourceware.org/bugzilla/show_bug.cgi?id=31026",
        "https://sourceware.org/git/?p=glibc.git;a=commit;h=506ea57086bfb9ce3daff1c14246a1cb532aba0a",
        "https://joshua.hu/fuzzing-glibc-libresolv"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-617"
        ],
        "cna_assigner": "glibc",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/8xxx/CVE-2026-8674.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-8674",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 504320,
  "published_at": "2026-09-17T16:54:27.31+00:00"
}