CVE-2026-31962

Summary

HTSlib is a library for reading and writing bioinformatics file formats. CRAM is a compressed format which stores DNA sequence alignment data. While most alignment records store DNA sequence and quality values, the format also allows them to omit this data in certain cases to save space. Due to some quirks of the CRAM format, it is necessary to handle these records carefully as they will actually store data that needs to be consumed and then discarded. Unfortunately the cram_decode_seq() did not handle this correctly in some cases. Where this happened it could result in reading a single byte from beyond the end of a heap allocation, followed by writing a single attacker-controlled byte to the same location. 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.

Affected Software

VendorProductVersion RangeStatus
samtoolshtslib< 1.21.1affected
samtoolshtslib>= 1.22, < 1.22.2affected
samtoolshtslib= 1.23affected

Weaknesses

  • CWE-122: CWE-122: Heap-based Buffer Overflow
  • CWE-125: CWE-125: Out-of-bounds Read
  • CWE-129: CWE-129: Improper Validation of Array Index
  • CWE-787: CWE-787: Out-of-bounds Write

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: yes
    • Technical Impact: partial

References