{"id":"CVE-2026-107729","state":"PUBLISHED","title":"SumatraPDF: Unsigned-to-signed hdrLen validation bypass in SumatraPDF MOBI parsing causes out-of-bounds read","description":"SumatraPDF is a multi-format reader for Windows. In 3.7.0.22298, src/MobiDoc.cpp narrows the untrusted unsigned mobiHdr.hdrLen field to a signed integer for validation; values above INT_MAX become negative and bypass the upper-bound check. When the EXTH flag is set, the original unsigned value is reused as a pointer offset, causing DecodeExthHeader() to read beyond the record buffer. Opening a crafted MOBI file can reliably terminate the application with a native access violation; no code execution, information disclosure, or integrity impact has been demonstrated. No fixed version is available as of this review.","publishedAt":"2026-10-08T22:18:40.609Z","updatedAt":"2026-10-09T15:46:45.488Z","severity":{"score":5.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","source":"GitHub_M"},"assigner":"GitHub_M","products":["sumatrapdfreader sumatrapdf"],"affected":[{"vendor":"sumatrapdfreader","product":"sumatrapdf","versions":[{"version":"<= 3.7.0.22298","status":"affected"}]}],"references":["https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-86hq-m6hv-67h2","https://github.com/sumatrapdfreader/sumatrapdf/commit/1ef900cbad02f06353b0a0747b098ca596f7c131"],"weaknesses":["CWE-125"],"ingestedAt":"2026-10-29T20:10:23.711Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/107xxx/CVE-2026-107729.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-107729","state":"PUBLISHED","datePublished":"2026-10-08T22:18:40.609Z","dateUpdated":"2026-10-09T15:46:45.488Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-10-08T17:21:52.976Z"},"containers":{"cna":{"title":"SumatraPDF: Unsigned-to-signed hdrLen validation bypass in SumatraPDF MOBI parsing causes out-of-bounds read","descriptions":[{"lang":"en","value":"SumatraPDF is a multi-format reader for Windows. In 3.7.0.22298, src/MobiDoc.cpp narrows the untrusted unsigned mobiHdr.hdrLen field to a signed integer for validation; values above INT_MAX become negative and bypass the upper-bound check. When the EXTH flag is set, the original unsigned value is reused as a pointer offset, causing DecodeExthHeader() to read beyond the record buffer. Opening a crafted MOBI file can reliably terminate the application with a native access violation; no code execution, information disclosure, or integrity impact has been demonstrated. No fixed version is available as of this review."}],"affected":[{"vendor":"sumatrapdfreader","product":"sumatrapdf","versions":[{"version":"<= 3.7.0.22298","status":"affected"}]}],"references":[{"url":"https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-86hq-m6hv-67h2","name":"https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-86hq-m6hv-67h2","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/sumatrapdfreader/sumatrapdf/commit/1ef900cbad02f06353b0a0747b098ca596f7c131","name":"https://github.com/sumatrapdfreader/sumatrapdf/commit/1ef900cbad02f06353b0a0747b098ca596f7c131","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":5.5,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"REQUIRED","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-125","lang":"en","description":"CWE-125: Out-of-bounds Read","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-10-08T22:18:40.609Z"},"source":{"advisory":"GHSA-86hq-m6hv-67h2","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-10-09T15:46:37.434740Z","id":"CVE-2026-107729","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":"2026-10-09T15:46:45.488Z"}}]}}}