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Vulnerability record · CVE-2026-31965 · published 18 March 2026

CVE-2026-31965: Htslib out-of-bounds read vulnerability

HHtslib · Htslib

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.

6.9 CVSS 4.0 Medium EPSS 0.45% · top 63.2% CWE-125 · Out-of-bounds readCWE-129 · CWE-129
6.9CVSS 4.0 base score
0.45%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

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:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/samtools/htslib/commit/9cefb46453ad471e933b8212d4f45920524d3357 Patch
https://github.com/samtools/htslib/security/advisories/GHSA-mqm2-v645-3qhr PatchVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

9.8CVE-2018-13845Htslib out-of-bounds read vulnerabilityAn issue has been found in HTSlib 1.8. It is a buffer over-read in sam_parse1 in sam.c.EPSS 1.6%9.8CVE-2017-1000206Htslib memory buffer overflow vulnerabilitysamtools htslib library version 1.4.0 and earlier is vulnerable to buffer overflow in the CRAM rANS codec resulting in potential arbitrary code execu…EPSS 2.0%8.8CVE-2026-31968Htslib stack-based buffer overflow vulnerabilityHTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data using a…EPSS 0.52%8.8CVE-2026-31963Htslib heap-based buffer overflow vulnerabilityHTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. As one…EPSS 0.52%8.8CVE-2026-31962Htslib heap-based buffer overflow vulnerabilityHTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. While …EPSS 0.59%8.8CVE-2020-36403Htslib out-of-bounds write vulnerabilityHTSlib through 1.10.2 allows out-of-bounds write access in vcf_parse_format (called from vcf_parse and vcf_read).EPSS 1.6%7.5CVE-2018-13843Htslib vulnerabilityAn issue has been found in HTSlib 1.8. It is a memory leak in bgzf_getline in bgzf.c. NOTE: the software maintainer's position is that the "failure t…EPSS 1.5%7.5CVE-2018-13844Htslib memory leak vulnerabilityAn issue has been found in HTSlib 1.8. It is a memory leak in fai_read in faidx.c. NOTE: This has been disputed with the assertion that this vulnerab…EPSS 1.4%

Source: NIST National Vulnerability Database (record CVE-2026-31965), CISA KEV, FIRST EPSS (scores of 2026-09-28). This page is refreshed as NVD updates the record.