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.
Metrics
CVSS 3.1 4.4/10
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:LWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| samtools | htslib | <= 1.24 |
References
- https://github.com/samtools/htslib
- https://github.com/samtools/htslib/blob/1.24/bgzf.c#L2504
- https://github.com/samtools/htslib/commit/18dddf02bb2c0053b32acec427723555a24b2873
- https://github.com/samtools/htslib/issues/2113
- https://github.com/samtools/htslib/pull/2057
- https://hackmd.io/@haindpwn/htslib-bgzf-gzi-int-truncation-oob
- https://www.vulncheck.com/advisories/htslib-through-1.24-heap-out-of-bounds-write-via-truncated-gzi-index-count
Timeline
- Published
- Oct 26, 2026
- Last modified
- Oct 27, 2026
- NVD status
- Deferred