CVE-2026-31969CWE-122CWE-787

HTSlib CRAM decoder has a heap buffer overflow

High · published March 18, 2026

CVSS v4.0
7.1
EPSS
1%
Percentile
44.6
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v4.0
7.1 · HIGH
Vector
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
EPSS
0.00540 · 44.6th percentile
Weaknesses
CWE-122 · Heap-based Buffer Overflow; CWE-787 · Out-of-bounds Write
Published
2026-03-18T19:47Z
EPSS history
Timeline
  • 18 MAR 19:47Z
    HTSlib CRAM decoder has a heap buffer overflow
    cvelistv5