CVE-2026-116742

HTSlib through 1.24 Heap Out-of-Bounds Write via Truncated .gzi Index Count

Published Oct 26, 2026 CVSS 4.0 · 4.8 Medium EPSS < 1% KEV · Not listed
Description
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 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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Samtools
Samtools htslib
Vendors & Products Samtools
Samtools htslib
Type Values Removed Values Added
Description 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 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.
Title HTSlib through 1.24 Heap Out-of-Bounds Write via Truncated .gzi Index Count
First Time appeared Htslib
Htslib htslib
Weaknesses CWE-197
CPEs cpe:2.3:a:htslib:htslib:*:*:*:*:*:*:*:*
Vendors & Products Htslib
Htslib htslib
References
Metrics cvssV3_1

{'score': 4.4, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:L'}

cvssV4_0

{'score': 4.8, 'vector': 'CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Oct 27, 2026, 2:16 PM
Reserved
Oct 26, 2026, 8:23 PM
Status
Deferred
Published
Oct 26, 2026, 10:16 PM
Modified
Oct 27, 2026, 4:04 PM