CVE-2026-31965
HTSlib CRAM reader has out-of-bounds reads due to improper validation of input
HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. In the cram_decode_slice() function called while reading CRAM records, validation of the reference id field occurred too late, allowing two out of bounds reads to occur before the invalid data was detected. The bug does allow two values to be leaked to the caller, however as the function reports an error it may be difficult to exploit them. It is also possible that the program will crash due to trying to access invalid memory. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- Low
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
6.9
HTSlib CRAM reader has out-of-bounds reads due to improper validation of input
HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. In the cram_decode_slice() function called while reading CRAM records, validation of the reference id field occurred too late, allowing two out of bounds reads to occur before the invalid data was detected. The bug does allow two values to be leaked to the caller, however as the function reports an error it may be difficult to exploit them. It is also possible that the program will crash due to trying to access invalid memory. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.
- Record
CVE-2026-31965- CVSS 4.0
- 6.9 Medium
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 - Weakness
- CWE-125, CWE-129
- Updated
- 2026-11-02
EUVDEUVD-2026-12934
6.9
HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. In the cram_decode_slice() function called while reading CRAM records, validation of the reference id field occurred too late, allowing two out of bounds reads to occur before the invalid data was detected. The bug does allow two values to be leaked to the caller, however as the function reports an error it may be difficult to exploit them. It is also possible that the program will crash due to trying to access invalid memory. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.
- Record
EUVD-2026-12934- CVSS 4.0
- 6.9 Medium
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 - Updated
- 2026-11-02
NVD
6.9
HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. In the cram_decode_slice() function called while reading CRAM records, validation of the reference id field occurred too late, allowing two out of bounds reads to occur before the invalid data was detected. The bug does allow two values to be leaked to the caller, however as the function reports an error it may be difficult to exploit them. It is also possible that the program will crash due to trying to access invalid memory. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.
- Record
CVE-2026-31965- CVSS 4.0
- 6.9 Medium
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Weakness
- CWE-125, CWE-129
- Updated
- 2026-11-02
OSV
6.9
HTSlib CRAM reader has out-of-bounds reads due to improper validation of input
HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. In the cram_decode_slice() function called while reading CRAM records, validation of the reference id field occurred too late, allowing two out of bounds reads to occur before the invalid data was detected. The bug does allow two values to be leaked to the caller, however as the function reports an error it may be difficult to exploit them. It is also possible that the program will crash due to trying to access invalid memory. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.
- Record
CVE-2026-31965- CVSS 4.0
- 6.9 Medium
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 - Weakness
- CWE-125, CWE-129
- Updated
- 2026-11-02
OSVDEBIAN-CVE-2026-31965
8.2
HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. In the cram_decode_slice() function called while reading CRAM records, validation of the reference id field occurred too late, allowing two out of bounds reads to occur before the invalid data was detected. The bug does allow two values to be leaked to the caller, however as the function reports an error it may be difficult to exploit them. It is also possible that the program will crash due to trying to access invalid memory. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.
- Record
DEBIAN-CVE-2026-31965- CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2026-31965
6.9
HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. In the cram_decode_slice() function called while reading CRAM records, validation of the reference id field occurred too late, allowing two out of bounds reads to occur before the invalid data was detected. The bug does allow two values to be leaked to the caller, however as the function reports an error it may be difficult to exploit them. It is also possible that the program will crash due to trying to access invalid memory. Versions 1.23.1, 1.22.2 and 1.21.1 include fixes for this issue. There is no workaround for this issue.
- Record
UBUNTU-CVE-2026-31965- CVSS 4.0
- 6.9 Medium
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 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H - Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
htslibDebian:12 |
All versions, plus listed versions 1.16+ds-31.17+ds-0+exp11.17+ds-11.18+ds-0+exp11.18+ds-1 Show 15 moreShow less1.19+ds-0+exp01.19+ds-11.19+ds-1+exp11.19+ds-1.11.20+ds-11.20+ds-21.21+ds-0+exp11.21+ds-0+exp21.21+ds-11.22.1+ds-11.22.1+ds-21.22.1+ds2-11.24-11.24-21.24-3 |
None known |
htslibDebian:13 |
All versions, plus listed versions 1.21+ds-11.22.1+ds-11.22.1+ds-21.22.1+ds2-11.24-11.24-21.24-3 |
None known |
htslibDebian:14 |
before 1.24-2, plus listed versions 1.21+ds-11.22.1+ds-11.22.1+ds-21.22.1+ds2-11.24-1 |
1.24-2 |
htslibUbuntu:Pro:14.04:LTS |
All versions, plus listed versions 0.2.0~rc3-10.2.0~rc3-1ubuntu0.1~esm1 |
None known |
htslibUbuntu:Pro:16.04:LTS |
All versions, plus listed versions 1.2.1-11.2.1-21.2.1-2ubuntu11.2.1-2ubuntu1+esm1 |
None known |
htslibUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 1.5-11.5-4ubuntu11.6-3ubuntu11.6-41.6-4build11.7-21.7-2ubuntu0.1~esm1 |
None known |
htslibUbuntu:20.04:LTS |
All versions, plus listed versions 1.9-101.9-111.9-121.10.2-2ubuntu11.10.2-2ubuntu21.10.2-31.10.2-3ubuntu0.1 |
None known |
htslibUbuntu:22.04:LTS |
All versions, plus listed versions 1.13+ds-21.13+ds-2build1 |
None known |
htslibUbuntu:24.04:LTS |
All versions, plus listed versions 1.17+ds-11.18+ds-11.19+ds-1.1build21.19+ds-1.1build3 |
None known |
htslibUbuntu:25.10 |
All versions, plus listed versions 1.21+ds-1 |
None known |
htslibUbuntu:26.10 |
All versions, plus listed versions 1.22.1+ds2-11.22.1+ds2-1build1 |
None known |
htslibUbuntu:26.04:LTS |
All versions, plus listed versions 1.21+ds-11.22.1+ds2-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-31965 is a medium vulnerability (CVSS 6.9) in Htslib, published March 18, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.40%, the 34th percentile. Fixed in htslib 1.24-2.
References
github.com/samtools/htslib/security/advisories/GHSA-mqm2-v645-3qhr
github.com/samtools/htslib/commit/9cefb46453ad471e933b8212d4f45920524d3357
github.com/CVEProject/cvelistV5/tree/main/cves/2026/31xxx/CVE-2026-31965.json
nvd.nist.gov/vuln/detail/CVE-2026-31965
security-tracker.debian.org/tracker/CVE-2026-31965
ubuntu.com/security/CVE-2026-31965
cve.org/CVERecord?id=CVE-2026-31965