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Vulnerabilities

Vulnerability · CVE-2026-31970

HTSlib is a library for reading and writing bioinformatics file formats.

Published Mar 18, 2026 · catalog updated Jun 17, 2026 · HTSlib is a library

Check if you run it

No confirmed exploitation is on record for CVE-2026-31970. EPSS is 0.66%. Act only if a listed version of HTSlib is a library is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (HTSlib is a library).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.1
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.66%
Remediation
Advisory link
Affected products
cpe htslib/htslib

HTSlib is a library for reading and writing bioinformatics file formats. GZI files are used to index block-compressed GZIP [BGZF] files. In the GZI loading function, , it was possible to trigger an integer overflow, leading to an under- or zero-sized buffer being allocated to store the index. Sixteen zero bytes would then be written to this buffer, and, depending on the result of the overflow the rest of the file may also be loaded into the buffer as well. If the function did attempt to load the data, it would eventually fail due to not reading the expected number of records, and then try to free the overflowed heap buffer. 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. The easiest work-around is to discard any index files from untrusted sources, and use the option to recreate them.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe htslib/htslib1.23

How to fix CVE-2026-31970

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-31970. EPSS is 0.66%. Act only if a listed version of HTSlib is a library is installed.

Which versions are affected?

Compare what you have installed with 1.23. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-122: Heap-based Buffer Overflow; CWE-1284; CWE-131. EPSS 0.66%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 18, 2026 · NIST NVD

    Detected

    HTSlib is a library for reading and writing bioinformatics file formats. GZI files are used to index block-compressed GZIP [BGZF] files. In the GZI loading function, , it was possible to trigger an integer overflow, leading to an under- or zero-sized buffer being allocated to store the index. Sixteen zero bytes would then be written to this buffer, and, depending on the result of the overflow the

  2. Jun 17, 2026 · NIST NVD

    Updated

    HTSlib is a library for reading and writing bioinformatics file formats. GZI files are used to index block-compressed GZIP [BGZF] files. In the GZI loading function, , it was possible to trigger an integer overflow, leading to an under- or zero-sized buffer being allocated to store the index. Sixteen zero bytes would then be written to this buffer, and, depending on the result of the overflow the

Sources

  • CVE.orgVulnerability recordCVE-2026-31970

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-31970

    30-day exploitation probability 0.7%

    first.org
  • NIST NVDVulnerability recordCVE-2026-31970

    HTSlib is a library for reading and writing bioinformatics file formats. GZI files are used to index block-compressed GZIP [BGZF] files. In the GZI loading function, , it was possible to trigger an integer overflow, leading to an under- or zero-sized buf

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.