Vulnerability in Pyasn1
CVE-2026-119194
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.
Published .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Pyasn1 — versions >= 0.3.3, < 0.6.5
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-119194?
- CVE-2026-119194 is a high-severity vulnerability in Pyasn1, classified under Inefficient Algorithmic Complexity. CVSS score: 7.5/10. Published 2026-10-29.
- How severe is CVE-2026-119194?
- High severity. CVSS v3 base score is 7.5 out of 10.