{"id":"CVE-2026-116742","title":"HTSlib through 1.24 Heap Out-of-Bounds Write via Truncated .gzi Index Count","summary":"HTSlib through 1.24 contains a heap out-of-bounds write and read vulnerability in bgzf_index_load_hfile() in bgzf.c that allows attackers to corrupt heap memory by supplying a crafted .gzi index entry count. A count of 0xFFFFFFFF truncat…","severity":"medium","cvss":4.4,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L","cvssSource":"cna","cwe":["CWE-197"],"vendor":"samtools","product":"htslib","affected":["htslib <= 1.24"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-10-27T13:42:04.833817Z"},"published":"2026-10-26","updated":"2026-10-27","sourceUpdated":"2026-10-27T14:16:48.820Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-116742","references":[{"url":"https://github.com/samtools/htslib/pull/2057","label":"Pull Request #2057"},{"url":"https://github.com/samtools/htslib/commit/18dddf02bb2c0053b32acec427723555a24b2873","label":"Patch Commit"},{"url":"https://github.com/samtools/htslib"},{"url":"https://github.com/samtools/htslib/blob/1.24/bgzf.c#L2504"},{"url":"https://hackmd.io/@haindpwn/htslib-bgzf-gzi-int-truncation-oob"},{"url":"https://github.com/samtools/htslib/issues/2113"},{"url":"https://www.vulncheck.com/advisories/htslib-through-1.24-heap-out-of-bounds-write-via-truncated-gzi-index-count","label":"VulnCheck Advisory: HTSlib through 1.24 Heap Out-of-Bounds Write via Truncated .gzi Index Count"}],"tags":["cve.org"],"epss":0.00123,"epssPercentile":0.02077,"ingestedAt":"2026-10-27T16:11:59.456Z","slug":"CVE-2026-116742","body":"## Overview\n\nHTSlib through 1.24 contains a heap out-of-bounds write and read vulnerability in bgzf_index_load_hfile() in bgzf.c that allows attackers to corrupt heap memory by supplying a crafted .gzi index entry count. A count of 0xFFFFFFFF truncates noffs to zero, causing writes past a malloc(0) buffer and an offs[-1] read in bgzf_useek(), resulting in heap corruption or crashes in tools like samtools and bcftools.\n\n## Affected\n\n- `htslib <= 1.24`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":24,"depthScoreParts":{"impact":24.2,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}