Description
pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.3, the `pyasn1` library is vulnerable to a Denial of Service (DoS) attack caused by uncontrolled recursion when decoding ASN.1 data with deeply nested structures. An attacker can supply a crafted payload containing thousands of nested `SEQUENCE` (`0x30`) or `SET` (`0x31`) tags with "Indefinite Length" (`0x80`) markers. This forces the decoder to recursively call itself until the Python interpreter crashes with a `RecursionError` or consumes all available memory (OOM), crashing the host application. This is a distinct vulnerability from CVE-2026-23490 (which addressed integer overflows in OID decoding). The fix for CVE-2026-23490 (`MAX_OID_ARC_CONTINUATION_OCTETS`) does not mitigate this recursion issue. Version 0.6.3 fixes this specific issue.
Published: 2026-03-18
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service
Action: Immediate Patch
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories
Source ID Title
Debian DLA Debian DLA DLA-4557-1 pyasn1 security update
Debian DSA Debian DSA DSA-6194-1 pyasn1 security update
Github GHSA Github GHSA GHSA-jr27-m4p2-rc6r Denial of Service in pyasn1 via Unbounded Recursion
Ubuntu USN Ubuntu USN USN-8129-1 pyasn1 vulnerability
Ubuntu USN Ubuntu USN USN-8134-1 pyasn1 vulnerabilities
History

Fri, 01 May 2026 17:30:00 +0000

Type Values Removed Values Added
References

Sat, 21 Mar 2026 05:30:00 +0000

Type Values Removed Values Added
References

Fri, 20 Mar 2026 18:00:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:pyasn1:pyasn1:*:*:*:*:*:python:*:*

Thu, 19 Mar 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-835
References
Metrics threat_severity

None

cvssV3_0

{'score': 7.5, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Important


Wed, 18 Mar 2026 21:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 18 Mar 2026 12:15:00 +0000

Type Values Removed Values Added
First Time appeared Pyasn1
Pyasn1 pyasn1
Vendors & Products Pyasn1
Pyasn1 pyasn1

Wed, 18 Mar 2026 03:30:00 +0000

Type Values Removed Values Added
Description pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.3, the `pyasn1` library is vulnerable to a Denial of Service (DoS) attack caused by uncontrolled recursion when decoding ASN.1 data with deeply nested structures. An attacker can supply a crafted payload containing thousands of nested `SEQUENCE` (`0x30`) or `SET` (`0x31`) tags with "Indefinite Length" (`0x80`) markers. This forces the decoder to recursively call itself until the Python interpreter crashes with a `RecursionError` or consumes all available memory (OOM), crashing the host application. This is a distinct vulnerability from CVE-2026-23490 (which addressed integer overflows in OID decoding). The fix for CVE-2026-23490 (`MAX_OID_ARC_CONTINUATION_OCTETS`) does not mitigate this recursion issue. Version 0.6.3 fixes this specific issue.
Title pyasn1 Vulnerable to Denial of Service via Unbounded Recursion
Weaknesses CWE-674
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-01T16:21:04.773Z

Reserved: 2026-03-07T16:40:05.884Z

Link: CVE-2026-30922

cve-icon Vulnrichment

Updated: 2026-05-01T16:21:04.773Z

cve-icon NVD

Status : Modified

Published: 2026-03-18T04:17:18.397

Modified: 2026-05-01T17:16:21.950

Link: CVE-2026-30922

cve-icon Redhat

Severity : Important

Publid Date: 2026-03-18T02:29:45Z

Links: CVE-2026-30922 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-03-24T10:59:29Z

Weaknesses