HtslibApplication

CVE-2026-31967

CRITICAL · 9.1 CVSS v3.1 Published 2026-03-18
Fix available
A fix is available. Upgrade to 1.21.1 / 1.22.2 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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, the value of the mate reference id field was not validated. Later use of this value, for example when converting the data to SAM format, could result in the out of bounds array reads when looking up the corresponding reference name. If the array value obtained also happened to be a valid pointer, it would be interpreted as a string and an attempt would be made to write the data as part of the SAM record. This bug may allow information about program state to be leaked. It may also cause a program crash through an attempt 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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-125

The code reads past the end (or before the start) of a buffer, returning memory that was never meant to be exposed. Attackers use it to leak secrets like keys or to defeat memory-protection defences. Remediation is validating indices and lengths before every read.

General guidance for the out-of-bounds read class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
HtslibApplication
Affected:< 1.21.1>= 1.22, < 1.22.2= 1.23

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.21.1 / 1.22.2 or later
Fixed in 1.21.11.22.2
Vendor patch github.com →
Recommended fix High confidence

htslib version 1.23.1 (or 1.22.2 / 1.21.1 depending on compatibility requirements)

  1. 1. Identify all applications or services that depend on the vulnerable htslib library versions (< 1.21.1, 1.22.x < 1.22.2, or 1.23)
  2. 2. For each dependent application, obtain the compatible htslib version 1.23.1 (recommended), 1.22.2, or 1.21.1 from the official source: https://github.com/samtools/htslib/releases
  3. 3. Replace the vulnerable htslib library files (libhts.so or libhts.a depending on your build configuration) with the fixed version
  4. 4. Rebuild and recompile any applications that statically link against htslib to ensure they use the fixed library
  5. 5. Restart any running services that use htslib to load the corrected library
  6. 6. Test CRAM file processing functionality to confirm the vulnerability is remediated
Caveat Review htslib release notes between your current version and the target fixed version for any API/ABI changes that may affect dependent applications

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-31967 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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