HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data using a variety of encodings and compression methods. When reading data encoded using the BYTE_ARRAY_STOP method, an out-by-one error in the cram_byte_array_stop_decode_char() function check for a full output buffer could result in a single attacker-controlled byte being written beyond the end of a heap allocation. Exploiting this bug causes a heap buffer overflow. If a user opens a file crafted to exploit this issue, it could lead to the program crashing, or overwriting of data and heap structures in ways not expected by the program. It may be possible to use this to obtain arbitrary code execution. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.
CVE-2026-31969
This high-severity CVE scores 8.1 under NVD CVSS v3. EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.1
- EG Score
- 8.1(low)
- EG Risk
- 41(Track)EG Risk 41/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity81% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 26%
- KEV
- Not listed
Published
March 18, 2026
Last Modified
June 17, 2026
References (2)
- security-advisories@githubhttps://github.com/samtools/htslib/commit/88cdf69e4b83bb550ab4f6f7134892c2ad1978f4
- security-advisories@githubhttps://github.com/samtools/htslib/security/advisories/GHSA-q4cj-f4h5-fqgc
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 3× in last 7d / 3× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-28 15:36 UTCEPSS rescore
- 2026-07-27 14:41 UTCEG score recompute
- 2026-07-27 14:27 UTCOSV refresh
Related CVEs(same CWE)
Same CWE
10 shownCWE-787 · CWE-122
- CVE-2011-1807EG 10.0HIGH
- CVE-2004-0978EG 10.0EPSS p98HIGH
- CVE-2004-1287EG 10.0EPSS p97HIGH
- CVE-2004-0574EG 10.0EPSS p99HIGH
- CVE-2002-2227EG 10.0HIGH
- CVE-2006-10003EG 9.8CRITICAL
- CVE-2006-10002NVD 7.5EG 9.8CRITICAL
- CVE-2007-0158EG 9.8CRITICAL
- CVE-2007-0899EG 9.8CRITICAL
- CVE-2011-2462EG 9.8 KEVEPSS p100CRITICAL
Frequently asked(5)
What is CVE-2026-31969?
When was CVE-2026-31969 disclosed?
Is CVE-2026-31969 actively exploited?
What is the CVSS score of CVE-2026-31969?
How do I remediate CVE-2026-31969?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-31969
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