{"id":"CVE-2026-107738","summary":"SumatraPDF: Untrusted binary record offset used without lower-bound validation","details":"SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, ChmFile::GetCharZ() narrows file-controlled unsigned string offsets from /#WINDOWS and /#IVB to signed integers without a lower-bound check. An offset that becomes negative can make the function read before the /#STRINGS buffer, causing deterministic application termination. No broader impact is claimed beyond the advisory-supported conditions. No fixed version is available as of this review.","aliases":["GHSA-33jg-vxm6-8mxx"],"modified":"2026-10-10T07:06:10.070723117Z","published":"2026-10-08T22:35:30.475Z","database_specific":{"cwe_ids":["CWE-125"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107738.json","cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107738.json"},{"type":"ADVISORY","url":"https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-33jg-vxm6-8mxx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-107738"},{"type":"FIX","url":"https://github.com/sumatrapdfreader/sumatrapdf/commit/62254ed6d781ceb5cd16489bb423e7f591cd72c4"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/sumatrapdfreader/sumatrapdf","events":[{"introduced":"0"},{"fixed":"62254ed6d781ceb5cd16489bb423e7f591cd72c4"}],"database_specific":{"extracted_events":[{"introduced":"0"},{"last_affected":"3.6.1"}],"source":["AFFECTED_FIELD","REFERENCES"]}}],"versions":["3.2","3.1.2rel","3.0split","2.5split","2.4split","2.3split","2.2split","2.1split","2.0split","1.9split","1.8split","1.7split","1.6split","1.5split","1.4split"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-107738.json","vanir_signatures":[{"signature_type":"Line","signature_version":"v1","source":"https://github.com/sumatrapdfreader/sumatrapdf/commit/62254ed6d781ceb5cd16489bb423e7f591cd72c4","target":{"file":"src/ChmFile.cpp"},"deprecated":false,"digest":{"line_hashes":["300426981365801951799513052451881105245","44003461603035836753667947272880798217","191448402986654612790008150530317847510","180180430064954597980864822438408456421","146721603798329529223172946927666931111","165441435043455372111516623351820020634","94396864851667047463377388242734878832","251450456216546555062597820057147573120","22661630783992783968356480019813172758","211191342035911755034253341575008824875","128943154191505563207805769665393005696","1701251640089346248700938297385306289","279802294764128008045833890763108672347","241932673837966555736495986171706959117","158462343271890274731363222281517084689"],"threshold":0.9},"id":"CVE-2026-107738-a40734dd"},{"signature_version":"v1","source":"https://github.com/sumatrapdfreader/sumatrapdf/commit/62254ed6d781ceb5cd16489bb423e7f591cd72c4","target":{"file":"src/ChmFile.cpp","function":"GetCharZ"},"deprecated":false,"digest":{"function_hash":"312024343921472359672318793875743238885","length":386},"id":"CVE-2026-107738-c1b66f3c","signature_type":"Function"}],"vanir_signatures_modified":"2026-10-10T07:06:10Z"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"}]}