{"id":"CVE-2026-8674","state":"PUBLISHED","title":"Assertion failure in the DNS stub resolver with a long search domain","description":"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.","publishedAt":"2026-09-17T16:54:27.310Z","updatedAt":"2026-09-17T18:09:16.072Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","source":"glibc"},"assigner":"glibc","products":["The GNU C Library glibc"],"affected":[{"vendor":"The GNU C Library","product":"glibc","defaultStatus":"unaffected","versions":[{"version":"2.26","status":"affected","lessThanOrEqual":"2.44","versionType":"custom"}]}],"references":["https://sourceware.org/bugzilla/show_bug.cgi?id=31026","https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0021","https://sourceware.org/git/?p=glibc.git;a=commit;h=506ea57086bfb9ce3daff1c14246a1cb532aba0a","https://joshua.hu/fuzzing-glibc-libresolv","http://www.openwall.com/lists/oss-security/2026/09/17/4"],"weaknesses":["CWE-617"],"ingestedAt":"2026-10-29T20:13:26.108Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/8xxx/CVE-2026-8674.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-8674","state":"PUBLISHED","datePublished":"2026-09-17T16:54:27.310Z","dateUpdated":"2026-09-17T18:09:16.072Z","assignerShortName":"glibc","assignerOrgId":"3ff69d7a-14f2-4f67-a097-88dee7810d18","dateReserved":"2026-05-15T12:15:59.229Z"},"containers":{"cna":{"title":"Assertion failure in the DNS stub resolver with a long search domain","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."}],"affected":[{"vendor":"The GNU C Library","product":"glibc","defaultStatus":"unaffected","versions":[{"version":"2.26","status":"affected","lessThanOrEqual":"2.44","versionType":"custom"}]}],"references":[{"url":"https://sourceware.org/bugzilla/show_bug.cgi?id=31026","tags":["issue-tracking"]},{"url":"https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0021","tags":["vendor-advisory"]},{"url":"https://sourceware.org/git/?p=glibc.git;a=commit;h=506ea57086bfb9ce3daff1c14246a1cb532aba0a","tags":["patch"]},{"url":"https://joshua.hu/fuzzing-glibc-libresolv","tags":["technical-description"]}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV3_1":{"version":"3.1","attackVector":"ADJACENT_NETWORK","attackComplexity":"HIGH","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH","baseSeverity":"MEDIUM","baseScore":5.3,"vectorString":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-617","lang":"en","description":"CWE-617 Reachable Assertion","type":"CWE"}]}],"providerMetadata":{"shortName":"glibc","orgId":"3ff69d7a-14f2-4f67-a097-88dee7810d18","dateUpdated":"2026-09-17T16:54:27.310Z"},"datePublic":"2023-11-07T05:00:00.000Z","credits":[{"lang":"en","value":"Joshua Rogers","type":"finder"}],"source":{"discovery":"EXTERNAL"},"x_generator":{"engine":"Vulnogram 1.0.5"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-09-17T18:05:54.714741Z","id":"CVE-2026-8674","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-09-17T18:06:00.631Z"}},{"title":"CVE Program Container","references":[{"url":"http://www.openwall.com/lists/oss-security/2026/09/17/4"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2026-09-17T18:09:16.072Z"}}]}}}