Bug 2448751 (CVE-2026-31965)

Summary: CVE-2026-31965 htslib: HTSlib: Information disclosure or denial of service via out-of-bounds read in CRAM record processing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
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. This vulnerability, an out-of-bounds read, occurs in the `cram_decode_slice()` function when processing CRAM (Compressed Reference-oriented Alignment Map) records due to delayed validation of the reference ID field. A remote attacker could exploit this by providing a specially crafted CRAM file, potentially leading to the disclosure of two memory values or causing the program to crash, resulting in a Denial of Service (DoS).
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Bug Depends On: 2448844, 2448845, 2448843, 2448846, 2448847, 2448848    
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Description OSIDB Bzimport 2026-03-18 19:03:16 UTC 
HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. In the `cram_decode_slice()` function called while reading CRAM records, validation of the reference id field occurred too late, allowing two out of bounds reads to occur before the invalid data was detected. The bug does allow two values to be leaked to the caller, however as the function reports an error it may be difficult to exploit them. It is also possible that the program will crash due to trying to access invalid memory. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.