CVE-2017-1000206

What it actually does

Buffer overflow in the CRAM rANS codec of htslib 1.4.0 and earlier allows memory corruption that can result in arbitrary code execution.

Why it matters to the business

Organizations relying on legacy bioinformatics tools for genomic data processing face risk of system compromise and potential exposure of sensitive research or patient-derived sequence data, though low EPSS and absence from KEV indicate limited active exploitation.

How an attack unfolds

An attacker crafts a malicious CRAM file containing malformed rANS-encoded data; when the vulnerable htslib library parses or decompresses the file, the overflow occurs and attacker-supplied code is executed.

How to fix it

Upgrade htslib to a version newer than 1.4.0 that resolves the CRAM rANS buffer overflow; rebuild or reinstall any dependent applications such as samtools against the patched library.

How to confirm the fix worked

Confirm installed htslib version exceeds 1.4.0, recompile dependent tools, and verify correct handling of both valid and malformed CRAM test files without crashes or unexpected behavior.

Typical attack path

1. Obtain or generate a specially crafted CRAM file exploiting the rANS codec flaw
2. Deliver the file to a target system or workflow that invokes htslib parsing routines
3. Trigger processing of the file through normal bioinformatics pipelines
4. Achieve arbitrary code execution via the resulting buffer overflow

How to detect it

Examine application and system logs for segmentation faults or abnormal terminations during CRAM file handling; look for unexpected child processes or network connections spawned by tools that use htslib.

What your security team should do

• Inventory all deployments of htslib and samtools to identify versions 1.4.0 and earlier
• Schedule immediate upgrades for any internet-facing or high-value bioinformatics workloads
• Apply compensating controls such as file-type sandboxing until patches are applied
• Monitor upstream htslib releases and ecosystem dependents for continued maintenance status