Vulnerability details

CVE-2026-31969

samtools htslib

HTSlib CRAM decoder has a heap buffer overflow

CVSS 4.0
7.1High

Official 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_STOP` method, an out-by-one error in the `cram_byte_array_stop_decode_char()` function check for a full output buffer could result in a single attacker-controlled byte being written beyond the end of a heap allocation. Exploiting this bug causes a heap buffer overflow. If a user opens a file crafted to exploit this issue, it could lead to the program crashing, or overwriting of data and heap structures in ways not expected by 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.

CVSS scores

ScoreVersionSourceVector
7.1High 4.0 CVEProject cvelistV5 (CNA) (GitHub_M) CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N

Affected products

VendorProductVersionsSource
samtools htslib < 1.21.1 CVEProject cvelistV5 (CNA)
samtools htslib = 1.23 CVEProject cvelistV5 (CNA)
samtools htslib >= 1.22, < 1.22.2 CVEProject cvelistV5 (CNA)

References and advisories

2
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Details

Published
2026-03-18
Last updated
2026-03-18
State
Published
Assigner (CNA)
GitHub_M

Exploit prediction (EPSS)

0.35%
Probability of exploitation in 30 days
29.5%
Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable
No
Exploitation
None
Technical impact
Partial

Weaknesses (CWE)

  • CWE-122
    Heap-based Buffer Overflow
  • CWE-787
    Out-of-bounds Write