CVE-2026-59884

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER decoder shared by the CER and DER codecs parses long-form tags by accumulating continuation octets without an upper bound on the tag ID size, allowing a crafted input to force construction of an arbitrarily large integer with CPU cost growing quadratically and to trigger unhandled ValueError exceptions in Python 3.11+ error formatting paths. Any application decoding untrusted BER, CER, or DER input is affected. This issue is fixed in version 0.6.4.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://github.com/pyasn1/pyasn1/commit/628e36ecbb5277a3f01572ce418ef54271b165a5	Patch
https://github.com/pyasn1/pyasn1/releases/tag/v0.6.4	Release Notes
https://github.com/pyasn1/pyasn1/security/advisories/GHSA-m4p7-r5rc-7g4j	Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:pyasn1:pyasn1:*:*:*:*:*:python:*:*

History

No history.

Information

Published : 2026-07-14 17:17

Updated : 2026-07-21 14:37

NVD link : CVE-2026-59884

Mitre link : CVE-2026-59884

CVE.ORG link : CVE-2026-59884

JSON object : View

Products Affected

pyasn1

pyasn1

CWE

CWE-400

Uncontrolled Resource Consumption

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