🛡️ CVE-2026-31971 — htslib

🟠 CVSS 8.1 — High ✅ No Known Exploit CWE-121 NVD
8.1
CVSS Score
0 Low4 Medium7 High9 Critical10

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. When reading data encoded using the BYTE_ARRAY_LEN method, the cram_byte_array_len_decode() failed to validate that the amount of data being unpacked matched the size of the output buffer where it was to be stored. Depending on the data series being read, this could result either in a heap or a stack overflow with attacker-controlled bytes. 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.

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. A user must be tricked into taking some action. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity high, availability high.

Weakness class

CVE-2026-31971 is classified as CWE-121: Stack-based Buffer Overflow. An oversized write to a stack buffer overwrites saved state such as return addresses, which can redirect execution.

Affected software

CVE-2026-31971 is recorded against 1 package.

  • htslib

Timeline and source

Published on 18 March 2026 and last revised on 17 June 2026. No public exploit is currently recorded for this entry. A vendor advisory or fix has been published. Record sourced from NVD.

References

github.com
github.com

CVE-2026-31971 on other distributions

Each distribution ships its own build and its own fixed version. Pick the one you run:

Details

Severity HIGH
CVSS Score 8.1
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
CWE CWE-121
Public Exploit ✅ No
Source NVD
Published 2026-03-18
Updated 2026-08-11
Modified 2026-06-17

Affected Packages

Software From version Fixed in
htslib — —

Similar Threats

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