{"id":"CVE-2026-6091","state":"PUBLISHED","title":"Partial-chain verification accepts untrusted intermediate as trust anchor","description":"Partial-chain certificate verification may accept chains that terminate at a peer-supplied, untrusted intermediate certificate rather than a trusted anchor. An attacker could present a chain that ends at an intermediate they control and have it accepted as valid. This affects the OpenSSL compatibility certificate-path-building path (wolfSSL_X509_verify_cert / X509_STORE, OPENSSL_EXTRA) when the X509_V_FLAG_PARTIAL_CHAIN verify flag is enabled.","publishedAt":"2026-06-25T16:46:12.599Z","updatedAt":"2026-06-25T17:58:31.045Z","severity":{"score":6,"label":"Medium","version":"4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N","source":"wolfSSL"},"assigner":"wolfSSL","products":["wolfSSL wolfSSL"],"affected":[{"vendor":"wolfSSL","product":"wolfSSL","defaultStatus":"unaffected","versions":[{"version":"5.7.4","status":"affected","lessThanOrEqual":"5.9.1","versionType":"semver"}],"collectionURL":"https://github.com/wolfSSL/wolfssl"}],"references":["https://github.com/wolfSSL/wolfssl/pull/10170","https://www.wolfssl.com/docs/security-vulnerabilities/"],"weaknesses":["CWE-295"],"ingestedAt":"2026-10-29T20:12:49.727Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/6xxx/CVE-2026-6091.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-6091","state":"PUBLISHED","datePublished":"2026-06-25T16:46:12.599Z","dateUpdated":"2026-06-25T17:58:31.045Z","assignerShortName":"wolfSSL","assignerOrgId":"50d2cd11-d01a-48ed-9441-5bfce9d63b27","dateReserved":"2026-04-10T16:01:23.181Z"},"containers":{"cna":{"title":"Partial-chain verification accepts untrusted intermediate as trust anchor","descriptions":[{"lang":"en","value":"Partial-chain certificate verification may accept chains that terminate at a peer-supplied, untrusted intermediate certificate rather than a trusted anchor. An attacker could present a chain that ends at an intermediate they control and have it accepted as valid. This affects the OpenSSL compatibility certificate-path-building path (wolfSSL_X509_verify_cert / X509_STORE, OPENSSL_EXTRA) when the X509_V_FLAG_PARTIAL_CHAIN verify flag is enabled."}],"affected":[{"vendor":"wolfSSL","product":"wolfSSL","defaultStatus":"unaffected","versions":[{"version":"5.7.4","status":"affected","lessThanOrEqual":"5.9.1","versionType":"semver"}],"collectionURL":"https://github.com/wolfSSL/wolfssl"}],"references":[{"url":"https://github.com/wolfSSL/wolfssl/pull/10170","tags":["patch"]},{"url":"https://www.wolfssl.com/docs/security-vulnerabilities/"}],"metrics":[{"format":"CVSS","scenarios":[{"lang":"en","value":"GENERAL"}],"cvssV4_0":{"attackVector":"NETWORK","attackComplexity":"LOW","attackRequirements":"PRESENT","privilegesRequired":"LOW","userInteraction":"NONE","vulnConfidentialityImpact":"NONE","subConfidentialityImpact":"NONE","vulnIntegrityImpact":"HIGH","subIntegrityImpact":"NONE","vulnAvailabilityImpact":"NONE","subAvailabilityImpact":"NONE","exploitMaturity":"NOT_DEFINED","Safety":"NOT_DEFINED","Automatable":"NOT_DEFINED","Recovery":"NOT_DEFINED","valueDensity":"NOT_DEFINED","vulnerabilityResponseEffort":"NOT_DEFINED","providerUrgency":"NOT_DEFINED","version":"4.0","baseSeverity":"MEDIUM","baseScore":6,"vectorString":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-295","lang":"en","description":"CWE-295 Improper Certificate Validation","type":"CWE"}]}],"providerMetadata":{"shortName":"wolfSSL","orgId":"50d2cd11-d01a-48ed-9441-5bfce9d63b27","dateUpdated":"2026-06-25T16:46:12.599Z"},"credits":[{"lang":"en","value":"Dikai Zou","type":"finder"}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 1.0.2"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-25T17:58:24.366839Z","id":"CVE-2026-6091","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":"2026-06-25T17:58:31.045Z"}}]}}}