{"id":"CVE-2026-39853","state":"PUBLISHED","title":"osslsigncode has a Stack Buffer Overflow via Unbounded Digest Copy During Signature Verification","description":"osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.12, A stack buffer overflow vulnerability exists in osslsigncode in several signature verification paths. During verification of a PKCS#7 signature, the code copies the digest value from a parsed SpcIndirectDataContent structure into a fixed-size stack buffer  (mdbuf[EVP_MAX_MD_SIZE], 64 bytes) without validating that the source length fits within the destination buffer. This pattern is present in the verification handlers for PE, MSI, CAB, and script files. An attacker can craft a malicious signed file with an oversized digest field in SpcIndirectDataContent. When a user verifies such a file with osslsigncode verify, the unbounded memcpy can overflow the stack buffer and corrupt adjacent stack state. This vulnerability is fixed in 2.12.","publishedAt":"2026-04-09T15:50:26.548Z","updatedAt":"2026-04-09T16:15:19.583Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["mtrojnar osslsigncode"],"affected":[{"vendor":"mtrojnar","product":"osslsigncode","versions":[{"version":"< 2.12","status":"affected"}]}],"references":["https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-hx87-8754-xvh4","https://github.com/mtrojnar/osslsigncode/commit/cbee1e723c5a8547302bd841ad9943ed8144db68","https://github.com/mtrojnar/osslsigncode/releases/tag/2.12"],"weaknesses":["CWE-121","CWE-787"],"ingestedAt":"2026-10-29T20:11:50.837Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/39xxx/CVE-2026-39853.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-39853","state":"PUBLISHED","datePublished":"2026-04-09T15:50:26.548Z","dateUpdated":"2026-04-09T16:15:19.583Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-04-07T19:13:20.378Z"},"containers":{"cna":{"title":"osslsigncode has a Stack Buffer Overflow via Unbounded Digest Copy During Signature Verification","descriptions":[{"lang":"en","value":"osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.12, A stack buffer overflow vulnerability exists in osslsigncode in several signature verification paths. During verification of a PKCS#7 signature, the code copies the digest value from a parsed SpcIndirectDataContent structure into a fixed-size stack buffer  (mdbuf[EVP_MAX_MD_SIZE], 64 bytes) without validating that the source length fits within the destination buffer. This pattern is present in the verification handlers for PE, MSI, CAB, and script files. An attacker can craft a malicious signed file with an oversized digest field in SpcIndirectDataContent. When a user verifies such a file with osslsigncode verify, the unbounded memcpy can overflow the stack buffer and corrupt adjacent stack state. This vulnerability is fixed in 2.12."}],"affected":[{"vendor":"mtrojnar","product":"osslsigncode","versions":[{"version":"< 2.12","status":"affected"}]}],"references":[{"url":"https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-hx87-8754-xvh4","name":"https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-hx87-8754-xvh4","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/mtrojnar/osslsigncode/commit/cbee1e723c5a8547302bd841ad9943ed8144db68","name":"https://github.com/mtrojnar/osslsigncode/commit/cbee1e723c5a8547302bd841ad9943ed8144db68","tags":["x_refsource_MISC"]},{"url":"https://github.com/mtrojnar/osslsigncode/releases/tag/2.12","name":"https://github.com/mtrojnar/osslsigncode/releases/tag/2.12","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":7.8,"baseSeverity":"HIGH","confidentialityImpact":"HIGH","integrityImpact":"HIGH","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-121","lang":"en","description":"CWE-121: Stack-based Buffer Overflow","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-787","lang":"en","description":"CWE-787: Out-of-bounds Write","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-04-09T15:50:26.548Z"},"source":{"advisory":"GHSA-hx87-8754-xvh4","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-09T16:13:50.325421Z","id":"CVE-2026-39853","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-04-09T16:15:19.583Z"}}]}}}