Microsoft Security Response Center guidance
Vendor revision: Nov 3, 2026Release Notes
Vulnerability intelligence
CVE-2026-119194 and is rated High severity with a CVSS score of 7.5. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
Release Notes
pyasn1 is a generic ASN.1 library for Python. From 0.3.3 until 0.6.5, schemaless container decoding stores every decoded component's TagSet in a growing set even though only one-versus-multiple tag types must be distinguished.
Attacker-controlled BER, CER, or DER input contains many distinct long tag IDs whose TagSet hashes collide. Each later set insertion compares against an increasing number of earlier colliding tags in ConstructedPayloadDecoderBase._decodeComponentsSchemaless, producing quadratic CPU work while decoded values and order remain valid.
Repeated inputs can exhaust decoder CPU and reduce service availability. This issue is fixed in version 0.6.5.
Source: NVD