{"schemaVersion":3,"id":"CVE-2026-107729","aliases":[],"status":"published","duplicateOf":null,"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.","dates":{"published":"2026-10-08T22:18:40.609Z","modified":"2026-10-09T15:46:45.488Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":5.5,"severity":"medium","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":5.5,"severity":"medium","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"NVD","score":5.5,"severity":"medium","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","exploitability":null,"impact":null,"computed":false}]},"epss":{"probability":0.00146,"percentile":0.03494,"severity":"low","asOf":"2026-10-22T00:00:00.000Z","change":{"pp":null,"baselineDate":null,"baselineScore":null},"history":[{"date":"2026-10-09T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-21T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-22T00:00:00.000Z","score":0.00146,"percentile":0.03494}],"last30":[{"date":"2026-10-09T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-10T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-11T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-12T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-13T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-14T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-15T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-16T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-17T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-18T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-19T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-20T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-21T00:00:00.000Z","score":0.00146,"percentile":null},{"date":"2026-10-22T00:00:00.000Z","score":0.00146,"percentile":0.03494}]},"kev":{"state":"not-listed","entries":[],"listedCount":0,"totalCatalogs":3,"catalogs":[{"source":"cisa","label":"CISA","listed":false,"entry":null},{"source":"enisa","label":"ENISA","listed":false,"entry":null},{"source":"circl","label":"CIRCL","listed":false,"entry":null}]},"ransomware":{"state":"none-recorded","sources":[]},"exploits":[],"exploitCount":0,"weaknesses":[{"id":"CWE-125","name":"Out-of-bounds 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