Memory corruption via mismatched CRAM codec options
Published Mar 18, 2026 · Updated Mar 18, 2026
Buffer overflows in the HTSlib CRAM decoder allow attackers to corrupt memory or crash a process with a crafted CRAM file. In cram_varint_decode_init and cram_const_decode_init, unsupported VARINT and CONST output options select incompatible integer decoders instead of rejecting array contexts. Exploitation requires a consuming application to decode the file; writes of up to eight bytes can alter adjacent heap or stack data and control flow.
Summary
What happened
Buffer overflows in the HTSlib CRAM decoder allow attackers to corrupt memory or crash a process with a crafted CRAM file. In cram_varint_decode_init and cram_const_decode_init, unsupported VARINT and CONST output options select incompatible integer decoders instead of rejecting array contexts. Exploitation requires a consuming application to decode the file; writes of up to eight bytes can alter adjacent heap or stack data and control flow.
The record
- CVE
- CVE-2026-31968
- Published
- Mar 18, 2026
- Updated
- Mar 18, 2026
- Vendor
- Samtools
- Product
- HTSlib
- Classifications
- CWE-122, CWE-843, CWE-121, CWE-787, T1204.002
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 18, 2026CVE publishedPublication date reported by the CVE source.
- 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.
- Affected versionversion=< 1.21.1
- Affected versionversion=>= 1.22, < 1.22.2
- Affected versionversion== 1.23
What conditions does exploitation require?
What is affected?
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.
Weakness, pattern, technique
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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