CVE-2017-6891

What it actually does

Stack-based buffer overflow in asn1_find_node() within libtasn1 when parsing specially crafted ASN.1 assignments files.

Why it matters to the business

Applications relying on the library for ASN.1 processing may crash or allow arbitrary code execution when users handle malicious files, increasing risk of system compromise in environments with high package prevalence.

How an attack unfolds

An attacker creates a malformed assignments file that triggers the overflow in asn1_find_node during parsing; the victim is tricked into processing it via asn1Coding or other utilities linked to the vulnerable library version.

How to fix it

Upgrade all listed libtasn1 packages (libtasn1, libtasn1-dev, libtasn1-doc, libtasn1-progs) to the fixed versions provided for Chainguard and Wolfi distributions.

How to confirm the fix worked

Verify installed package versions against the fixed releases; attempt processing of known-good ASN.1 files with asn1Coding to confirm absence of crashes on boundary cases.

Typical attack path

1. Craft malicious ASN.1 assignments file exploiting asn1_find_node bounds error
2. Deliver file to target via email, download, or shared storage
3. Victim processes file with asn1Coding or dependent application
4. Overflow leads to control-flow hijacking or denial of service

How to detect it

Review process execution logs and crash reports for asn1Coding or linked applications; inspect file access patterns involving .asn1 or assignments files around any anomalous terminations.

What your security team should do

• Prioritize immediate upgrade of all affected libtasn1 packages to patched versions
• Restrict processing of untrusted ASN.1 assignments files in utilities and dependent applications
• Monitor for new library releases given the age of the original flaw and ecosystem usage