Bug 2448776 (CVE-2026-31968)

Summary: CVE-2026-31968 htslib: HTSlib: Buffer overflow in CRAM decoder
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: high    
Version: unspecifiedKeywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in HTSlib, a library for reading and writing bioinformatics file formats. Specifically, within the CRAM (Compressed Reference-oriented Alignment Map) format, incomplete validation of context in the VARINT and CONST encodings could lead to a heap or stack buffer overflow. A remote attacker could exploit this by convincing a user to open a specially crafted file, potentially causing the program to crash, overwrite data structures, alter program control flow, and possibly achieve arbitrary code execution.
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Bug Depends On: 2448874, 2448876, 2448878    
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Description OSIDB Bzimport 2026-03-18 20:02:17 UTC 
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.