CVE-2026-31965Network attack vector

Value disclosure or crash via late reference validation

Published Mar 18, 2026 · Updated Mar 18, 2026

Out-of-bounds reads in Samtools HTSlib 1.21 and earlier, 1.22 through 1.22.1, and 1.23 allow remote attackers to leak values or crash readers. The cram_decode_slice function decodes CRAM reference and mate-reference identifiers and uses them before confirming that they fall between -1 and the reference-count bound. A crafted CRAM file can expose two decoded values to the calling program or trigger an invalid-memory access and crash, although the decoder returns an error after detecting the invalid identifier.

CVSS severity6.9
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds reads in Samtools HTSlib 1.21 and earlier, 1.22 through 1.22.1, and 1.23 allow remote attackers to leak values or crash readers. The cram_decode_slice function decodes CRAM reference and mate-reference identifiers and uses them before confirming that they fall between -1 and the reference-count bound. A crafted CRAM file can expose two decoded values to the calling program or trigger an invalid-memory access and crash, although the decoder returns an error after detecting the invalid identifier.

The record

CVE
CVE-2026-31965
Published
Mar 18, 2026
Updated
Mar 18, 2026
Vendor
Samtools
Product
HTSlib
Classifications
CWE-125, CWE-129
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

8.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
6.9GitHub, Inc.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

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-125Out-of-bounds Read
CWE-129Improper Validation of Array Index

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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