CVE-2026-59885CWE-400CWE-407

pyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of service

High · published July 14, 2026

CVSS v3.1
7.5
EPSS
1%
Percentile
48.9
In the wild
Unconfirmed
What it is

pyasn1 is a generic ASN.1 library for Python. Prior to 0.6.4, the BER, CER, and DER decoders process OBJECT IDENTIFIER and RELATIVE-OID values in quadratic time relative to the number of arcs, so a small crafted payload containing an OID with many arcs consumes excessive CPU per decode() call and can deny service to applications that decode untrusted ASN.1 data. The corresponding encoders have the same quadratic behavior when an application re-encodes previously decoded attacker-supplied values. This issue is fixed in version 0.6.4.

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00616 · 48.9th percentile
Weaknesses
CWE-400 · Uncontrolled Resource Consumption; CWE-407 · Inefficient Algorithmic Complexity
Published
2026-07-14T16:40Z
EPSS history
Timeline
  • 14 JUL 16:40Z
    pyasn1: Quadratic complexity in OBJECT IDENTIFIER and RELATIVE-OID processing allows denial of service
    cvelistv5