HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. As one method of removing redundant data, CRAM uses reference-based compression so that instead of storing the full sequence for each alignment record it stores a location in an external reference sequence along with a list of differences to the reference at that location as a sequence of "features". When decoding these features, an out-by-one error in a test for CRAM features that appear beyond the extent of the CRAM record sequence could result in an invalid write of one attacker-controlled byte beyond the end of a 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. There is no workaround for this issue.

The remote Fedora 42 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-1fc0d39acd advisory.

    Update to 1.23.1

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has packages installed that are affected by multiple vulnerabilities as referenced in the FEDORA-2026-3b06345bf2 advisory.

    Update to 1.23.1

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which     stores DNA sequence alignment data. As one method of removing redundant data, CRAM uses reference-based     compression so that instead of storing the full sequence for each alignment record it stores a location in     an external reference sequence along with a list of differences to the reference at that location as a     sequence of features. When decoding these features, an out-by-one error in a test for CRAM features that     appear beyond the extent of the CRAM record sequence could result in an invalid write of one attacker-     controlled byte beyond the end of a 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. There is no     workaround for this issue. (CVE-2026-31963)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Severity
304032	Fedora 42 : bcftools / htslib / samtools (2026-1fc0d39acd)	Nessus	Fedora Local Security Checks	high
304024	Fedora 43 : bcftools / htslib / samtools (2026-3b06345bf2)	Nessus	Fedora Local Security Checks	high
302970	Linux Distros Unpatched Vulnerability : CVE-2026-31963	Nessus	Misc.	high

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CVE-2026-31963

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