# CVE-2026-31967: htslib: HTSlib is a library for reading and writing bioinformatics file formats

CVE-2026-31967 is fixed in htslib on 1 platform by DEBIAN-CVE-2026-31967 (version 1.24-2), released March 18, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-31967
- Priority: Urgent
- CVSS: 9.1 (critical)
- EPSS: 0.0047
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 18, 2026

## Description

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, the value of the mate reference id field was not validated. Later use of this value, for example when converting the data to SAM format, could result in the out of bounds array reads when looking up the corresponding reference name. If the array value obtained also happened to be a valid pointer, it would be interpreted as a string and an attempt would be made to write the data as part of the SAM record. This bug may allow information about program state to be leaked. It may also cause a program crash through an attempt 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | htslib Debian 14 | 1.24-2 | [DEBIAN-CVE-2026-31967](https://patchblox.com/security/data/fix/linux/debian-cve-2026-31967.md) | Mar 18, 2026 |

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