Denial of Service Vulnerability in pyasn1 Library by Python Software Foundation
CVE-2026-30922

7.5HIGH

Key Information:

Vendor

Pyasn1

Status
Pyasn1
Vendor
CVE Published:
18 March 2026

What is CVE-2026-30922?

The pyasn1 library, widely used for ASN.1 encoding in Python, prior to version 0.6.3 is susceptible to a Denial of Service attack. This vulnerability arises from uncontrolled recursion triggered when the library decodes ASN.1 data with highly nested structures. An adversary can exploit this weakness by sending specially crafted payloads with numerous nested SEQUENCE or SET tags. Such attacks can lead to severe resource exhaustion, culminating in crashes of the Python interpreter or targeted applications due to a RecursionError or out-of-memory conditions. Notably, addressing this issue was distinct from prior vulnerabilities like CVE-2026-23490, which focused on integer overflow scenarios. Version 0.6.3 introduces mitigation strategies for this specific recursion issue.

Affected Version(s)

pyasn1 < 0.6.3

References

https://github.com/pyasn1/pyasn1/security/advisories/GHSA...
x_refsource_CONFIRM
https://github.com/pyasn1/pyasn1/commit/25ad481c19fdb006e...
x_refsource_MISC

CVSS V3.1

Score:
7.5
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.