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Medium 6.9Published Mar 18, 2026

CVE-2026-31965HTSlib CRAM reader has out-of-bounds reads due to improper validation of input

Updated under an hour ago ()

Does this affect you?

It affects samtools htslib and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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.

CVSS
6.9 MEDIUM (v4.0, CNA)CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N
Weakness (CWE)
CWE-125, CWE-129
Known exploited
Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days)
Not loaded for this CVE
Assigned by
GitHub_M
NVD analysis
Analyzed
Record last updated
Mar 19, 2026
First seen by InfoSec Signals
Oct 9, 2026

Affected products

Affected products
samtools htslib
samtools:htslib (from the name)
before 1.21.1; from 1.22, < 1.22.2; = 1.23
CNA record
htslib htslib
htslib:htslib
before 1.21.1; from 1.22 before 1.22.2; 1.23
NVD

References

References

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.

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