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Description

HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data using a variety of encodings and compression methods. For the `VARINT` and `CONST` encodings, incomplete validation of the context in which the encodings were used could result in up to eight bytes being written beyond the end of a heap allocation, or up to eight bytes being written to the location of a one byte variable on the stack, possibly causing the values to adjacent variables to change unexpectedly. Depending on the data stream this could result either in a heap buffer overflow or a stack overflow. If a user opens a file crafted to exploit this issue it could lead to the program crashing, overwriting of data structures on the heap or stack in ways not expected by the program, or changing the control flow of the program. It may be possible to use this to obtain arbitrary code execution. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.

PUBLISHED Reserved 2026-03-10 | Published 2026-03-18 | Updated 2026-03-18 | Assigner GitHub_M




HIGH: 8.8CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N

Problem types

CWE-121: Stack-based Buffer Overflow

CWE-122: Heap-based Buffer Overflow

CWE-787: Out-of-bounds Write

CWE-843: Access of Resource Using Incompatible Type ('Type Confusion')

Product status

< 1.21.1
affected

>= 1.22, < 1.22.2
affected

= 1.23
affected

References

github.com/...htslib/security/advisories/GHSA-cgcm-c9r2-p57j

github.com/...ommit/0ec436796eca7b4ce7fcc9b77270c102da29bb2e

cve.org (CVE-2026-31968)

nvd.nist.gov (CVE-2026-31968)

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