GHSA-fm9c-5rcf-2q5p: pyasn1 (CVE-2026-119194)

Package	Ecosystem	Affected	Fixed in
pyasn1	PyPI	>=0.3.3, <0.6.5	0.6.5

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Versions 0.3.3 up to but not including 0.6.5 of the Python package pyasn1 are affected. When an application decodes attacker-controlled BER, CER, or DER data without an ASN.1 schema, a container holding many long tag IDs with colliding hashes can cause quadratic CPU use, so an attacker only needs to supply such input to the decoder. The impact is reduced availability through CPU exhaustion; the source reports no confidentiality or integrity effect. Upgrade to pyasn1 0.6.5, which is listed as the fixed version.

Written 31 Oct 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
7.5	High	3.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0043, the 36th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

29 Oct 2026, 19:38 UTC Confirmed by the CVE List
29 Oct 2026, 20:17 UTC Confirmed by NVD
31 Oct 2026, 14:07 UTC First seen by agentprime
31 Oct 2026, 14:07 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.