CVE-2026-59884
Published:July 14, 2026
Updated:August 04, 2026
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.
Affected Packages
pyasn1 (CONDA):
Affected version(s) >=0.1.4 <0.6.4Fix Suggestion:
Update to version 0.6.4pyasn1 (CONDA):
Affected version(s) >=0.1.4 <0.6.4Fix Suggestion:
Update to version 0.6.4https://github.com/pyasn1/pyasn1.git (GITHUB):
Affected version(s) >=v0.2.1 <v0.6.4Fix Suggestion:
Update to version v0.6.4pyasn1 (PYTHON):
Affected version(s) >=0.0.6a <0.6.4Fix Suggestion:
Update to version 0.6.4pyasn1 (PYTHON):
Affected version(s) >=0.0.6a <0.6.4Fix Suggestion:
Update to version 0.6.4Related Resources (7)
Do you need more information?
Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Uncontrolled Resource Consumption
EPSS
Base Score:
0.35