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.
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
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

References
Link Providers
http://www.openwall.com/lists/oss-security/2026/03/20/4 cve-icon
https://access.redhat.com/errata/RHSA-2026:10184 cve-icon
https://access.redhat.com/errata/RHSA-2026:12176 cve-icon
https://access.redhat.com/errata/RHSA-2026:13508 cve-icon
https://access.redhat.com/errata/RHSA-2026:13512 cve-icon
https://access.redhat.com/errata/RHSA-2026:13545 cve-icon
https://access.redhat.com/errata/RHSA-2026:13553 cve-icon
https://access.redhat.com/errata/RHSA-2026:13902 cve-icon
https://access.redhat.com/errata/RHSA-2026:13916 cve-icon
https://access.redhat.com/errata/RHSA-2026:13917 cve-icon
https://access.redhat.com/errata/RHSA-2026:14020 cve-icon
https://access.redhat.com/errata/RHSA-2026:16009 cve-icon
https://access.redhat.com/errata/RHSA-2026:17083 cve-icon
https://access.redhat.com/errata/RHSA-2026:17611 cve-icon
https://access.redhat.com/errata/RHSA-2026:19138 cve-icon
https://access.redhat.com/errata/RHSA-2026:19355 cve-icon
https://access.redhat.com/errata/RHSA-2026:19375 cve-icon
https://access.redhat.com/errata/RHSA-2026:19712 cve-icon
https://access.redhat.com/errata/RHSA-2026:20588 cve-icon
https://access.redhat.com/errata/RHSA-2026:22131 cve-icon
https://access.redhat.com/errata/RHSA-2026:22132 cve-icon
https://access.redhat.com/errata/RHSA-2026:22133 cve-icon
https://access.redhat.com/errata/RHSA-2026:22134 cve-icon
https://access.redhat.com/errata/RHSA-2026:22135 cve-icon
https://access.redhat.com/errata/RHSA-2026:22969 cve-icon
https://access.redhat.com/errata/RHSA-2026:22970 cve-icon
https://access.redhat.com/errata/RHSA-2026:22987 cve-icon
https://access.redhat.com/errata/RHSA-2026:24761 cve-icon
https://access.redhat.com/errata/RHSA-2026:24762 cve-icon
https://access.redhat.com/errata/RHSA-2026:37275 cve-icon
https://access.redhat.com/errata/RHSA-2026:41928 cve-icon
https://access.redhat.com/errata/RHSA-2026:6309 cve-icon
https://access.redhat.com/errata/RHSA-2026:6568 cve-icon
https://access.redhat.com/errata/RHSA-2026:6720 cve-icon
https://access.redhat.com/errata/RHSA-2026:6912 cve-icon
https://access.redhat.com/errata/RHSA-2026:6926 cve-icon
https://access.redhat.com/errata/RHSA-2026:8437 cve-icon
https://access.redhat.com/security/cve/CVE-2026-30922 cve-icon
https://bugzilla.redhat.com/show_bug.cgi?id=2448553 cve-icon
https://github.com/pyasn1/pyasn1/commit/25ad481c19fdb006e20485ef3fc2e5b3eff30ef0 cve-icon cve-icon cve-icon
https://github.com/pyasn1/pyasn1/security/advisories/GHSA-jr27-m4p2-rc6r cve-icon cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2026/05/msg00001.html cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-30922 cve-icon
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-30922.json cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-30922 cve-icon
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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-08-12T12:04:47.064Z

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: 2026-08-12T12:18:26.713

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