NULL pointer dereference in samtools cram-size

Description

SAMtools is a program for reading, manipulating and writing bioinformatics file formats. Starting in version 1.17, in the cram-size command, used to write information about how well CRAM files are compressed, a check to see if the `cram_decode_compression_header()` was missing. If the function returned an error, this could lead to a NULL pointer dereference. Exploiting this bug causes a NULL pointer dereference. Typically this will cause the program to crash. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.

Scores

EPSS (exploitation in 30 days)

0.56% · top 53% of all CVEs (6 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.9.

Weakness

• CWE-476: NULL Pointer Dereference (opens in a new tab)All about CWE-476 and its CVEs

Affected products

• samtools · samtools

  • affected >= 1.17, < 1.21.1
  • affected >= 1.22, < 1.22.2
  • affected = 1.23

References (3)

• https://github.com/samtools/samtools/security/advisories/GHSA-x86f-q6fj-cm43 (opens in a new tab)x_refsource_CONFIRM
• https://github.com/samtools/samtools/commit/06fc2a219b3d7c94d3f412c09f6d1efd51199f2f (opens in a new tab)x_refsource_MISC
• http://www.openwall.com/lists/oss-security/2026/03/18/12 (opens in a new tab)

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-31973](https://trackcve.app/badge/CVE-2026-31973.svg)](https://trackcve.app/cve/CVE-2026-31973)

Record last updated 19 Mar 2026, 16:14 UTC.