{"id":"CVE-2026-34610","state":"PUBLISHED","title":"leancrypto: Integer truncation in X.509 name parser enables certificate identity impersonation","description":"The leancrypto library is a cryptographic library that exclusively contains only PQC-resistant cryptographic algorithms. Prior to version 1.7.1, lc_x509_extract_name_segment() casts size_t vlen to uint8_t when storing the Common Name (CN) length. An attacker who crafts a certificate with CN = victim's CN + 256 bytes padding gets cn_size = (uint8_t)(256 + N) = N, where N is the victim's CN length. The first N bytes of the attacker's CN are the victim's identity. After parsing, the attacker's certificate has an identical CN to the victim's — enabling identity impersonation in PKCS#7 verification, certificate chain matching, and code signing. This issue has been patched in version 1.7.1.","publishedAt":"2026-04-02T17:54:53.250Z","updatedAt":"2026-04-03T17:25:10.195Z","severity":{"score":5.9,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["smuellerDD leancrypto"],"affected":[{"vendor":"smuellerDD","product":"leancrypto","versions":[{"version":"< 1.7.1","status":"affected"}]}],"references":["https://github.com/smuellerDD/leancrypto/security/advisories/GHSA-636g-jxv4-v4gr","https://github.com/smuellerDD/leancrypto/commit/5cdcbe12bd6c3d6e87e969972a580b44a74c3a6a","https://github.com/smuellerDD/leancrypto/releases/tag/v1.7.1"],"weaknesses":["CWE-681"],"ingestedAt":"2026-10-29T20:11:40.391Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/34xxx/CVE-2026-34610.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-34610","state":"PUBLISHED","datePublished":"2026-04-02T17:54:53.250Z","dateUpdated":"2026-04-03T17:25:10.195Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-03-30T17:15:52.500Z"},"containers":{"cna":{"title":"leancrypto: Integer truncation in X.509 name parser enables certificate identity impersonation","descriptions":[{"lang":"en","value":"The leancrypto library is a cryptographic library that exclusively contains only PQC-resistant cryptographic algorithms. Prior to version 1.7.1, lc_x509_extract_name_segment() casts size_t vlen to uint8_t when storing the Common Name (CN) length. An attacker who crafts a certificate with CN = victim's CN + 256 bytes padding gets cn_size = (uint8_t)(256 + N) = N, where N is the victim's CN length. The first N bytes of the attacker's CN are the victim's identity. After parsing, the attacker's certificate has an identical CN to the victim's — enabling identity impersonation in PKCS#7 verification, certificate chain matching, and code signing. This issue has been patched in version 1.7.1."}],"affected":[{"vendor":"smuellerDD","product":"leancrypto","versions":[{"version":"< 1.7.1","status":"affected"}]}],"references":[{"url":"https://github.com/smuellerDD/leancrypto/security/advisories/GHSA-636g-jxv4-v4gr","name":"https://github.com/smuellerDD/leancrypto/security/advisories/GHSA-636g-jxv4-v4gr","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/smuellerDD/leancrypto/commit/5cdcbe12bd6c3d6e87e969972a580b44a74c3a6a","name":"https://github.com/smuellerDD/leancrypto/commit/5cdcbe12bd6c3d6e87e969972a580b44a74c3a6a","tags":["x_refsource_MISC"]},{"url":"https://github.com/smuellerDD/leancrypto/releases/tag/v1.7.1","name":"https://github.com/smuellerDD/leancrypto/releases/tag/v1.7.1","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"HIGH","attackVector":"NETWORK","availabilityImpact":"NONE","baseScore":5.9,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-681","lang":"en","description":"CWE-681: Incorrect Conversion between Numeric Types","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-04-02T17:54:53.250Z"},"source":{"advisory":"GHSA-636g-jxv4-v4gr","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-03T17:03:26.975851Z","id":"CVE-2026-34610","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":"2026-04-03T17:25:10.195Z"}}]}}}