CVE-2026-30922 pyasn1 CVE debrief

Who should care

System administrators and developers using pyasn1 should assess exposure and apply the fix to prevent potential DoS attacks. This includes reviewing system logs for suspicious activity, performing vulnerability scanning and penetration testing, and implementing compensating controls. Security teams should prioritize updating pyasn1 to version 0.6.3 or later and monitor for potential DoS attacks.

Why it matters

CVE-2026-30922 is a high-severity vulnerability in pyasn1 that can lead to DoS attacks. Defenders should prioritize updating to version 0.6.3 or later.

• Potential DoS attacks due to uncontrolled recursion
• System crashes or memory consumption due to deeply nested ASN.1 structures
• Need for urgent patching to prevent exploitation
• Verification of pyasn1 version and system exposure

Technical summary

The pyasn1 library for Python is vulnerable to a DoS attack due to uncontrolled recursion when decoding ASN.1 data with deeply nested structures. An attacker can supply a crafted payload containing thousands of nested SEQUENCE or SET tags with Indefinite Length markers, causing the decoder to recursively call itself until the Python interpreter crashes or consumes all available memory. The fix for CVE-2026-23490 does not mitigate this recursion issue. Version 0.6.3 of the pyasn1 library fixes this specific issue. Defenders should prioritize updating pyasn1 to version 0.6.3 or later to prevent potential DoS attacks.

Defensive priority

Defenders should prioritize updating pyasn1 to version 0.6.3 or later to prevent potential DoS attacks. System administrators and developers using pyasn1 should assess exposure and apply the fix.

Recommended defensive actions

• Update pyasn1 to version 0.6.3 or later
• Assess exposure and apply the fix
• Monitor for potential DoS attacks
• Review system logs for suspicious activity
• Perform vulnerability scanning and penetration testing to identify potential weaknesses
• Implement compensating controls, such as rate limiting and IP blocking
• Develop an incident response plan in case of a successful attack

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. Multiple Red Hat errata and GitHub advisories offer additional context and patches. The vulnerability has been publicly disclosed and defenders should prioritize updating pyasn1 to version 0.6.3 or later. Evidence of the vulnerability's existence and impact can be found in the CVE record and NVD entry.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.