CVE-2026-31964Network attack vector

Process crash via NULL decoder output writes

Published Mar 18, 2026 · Updated Mar 18, 2026

NULL pointer dereference in HTSlib before 1.21.1, 1.22 through 1.22.1, and 1.23 allows remote attackers to crash CRAM consumers. The CONST, XPACK, and XRLE decoders in cram/cram_codecs.c write through a NULL output pointer instead of consuming and discarding encoded data. Exploitation requires a CRAM record that omits sequence or quality data while using one of those encodings; the bounded consequence is a process crash.

CVSS severity6.9
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

NULL pointer dereference in HTSlib before 1.21.1, 1.22 through 1.22.1, and 1.23 allows remote attackers to crash CRAM consumers. The CONST, XPACK, and XRLE decoders in cram/cram_codecs.c write through a NULL output pointer instead of consuming and discarding encoded data. Exploitation requires a CRAM record that omits sequence or quality data while using one of those encodings; the bounded consequence is a process crash.

The record

CVE
CVE-2026-31964
Published
Mar 18, 2026
Updated
Mar 18, 2026
Vendor
Samtools
Product
HTSlib
Classifications
CWE-476, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 18, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 1.21.1
  2. Affected versionversion=>= 1.22, < 1.22.2
  3. Affected versionversion== 1.23

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Samtools · HTSlibversion=< 1.21.1; version=>= 1.22, < 1.22.2; version== 1.23

Published CVSS scores

6.9GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-476NULL Pointer Dereference
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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