CVE-2026-30922

HIGH EPSS 43.4%
Published Mar 18, 20263mo ago · Modified Jun 17, 20262w ago
7.5 CVSS 3.1
High
Find Similar
Published Mar 18, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
7.5
Exploitability
3.9
Impact
3.6
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality None
Integrity None
Availability High

Threat Intelligence

EPSS Exploit Probability
43.4% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 1

CWE-674

Affected Products 1

VendorProductVersionRange
pyasn1pyasn1* <0.6.3

References 4

  • openwall.com http://www.openwall.com/lists/oss-security/2026/03/20/4
  • github.com https://github.com/pyasn1/pyasn1/commit/25ad481c19fdb006e20485ef3fc2e5b3eff30ef0
    Patch
  • github.com https://github.com/pyasn1/pyasn1/security/advisories/GHSA-jr27-m4p2-rc6r
    ExploitVendor Advisory
  • lists.debian.org https://lists.debian.org/debian-lts-announce/2026/05/msg00001.html

Remediation

  • github.com https://github.com/pyasn1/pyasn1/commit/25ad481c19fdb006e20485ef3fc2e5b3eff30ef0
    Patch