CVE-2026-59884

Publication date 14 July 2026

Last updated 1 September 2026

Ubuntu priority

Cvss 3 Severity Score

Description

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.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
pyasn1	26.10 stonking	Not affected
	26.04 LTS resolute	Fixed in 0.6.3-1ubuntu0.1
	24.04 LTS noble	Fixed in 0.4.8-4ubuntu0.3
	22.04 LTS jammy	Fixed in 0.4.8-1ubuntu0.3
	20.04 LTS focal	Needs evaluation
	18.04 LTS bionic	Needs evaluation
	16.04 LTS xenial	Needs evaluation
	14.04 LTS trusty	Needs evaluation

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
pyasn1	Upstream: 628e36e

Severity score breakdown

CVSS version: CVSS v3.0

Base score 7.5 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High

Scores

Parameter	Value
Base score	7.5 · High
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

USN-8712-1
pyasn1 vulnerabilities
1 September 2026

USN-9011-1
pyasn1 vulnerabilities
9 November 2026