GHSA-8m4g-j4wp-wgcg: authlib (CVE-2026-114616)

Package	Ecosystem	Affected	Fixed in
authlib	PyPI	<1.9.1	1.9.1

Machine-written summary

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

Authlib versions before 1.9.1 accept an empty symmetric (oct) key for HMAC signing and verification with HS256, HS384 and HS512, so a token signed with that empty key is accepted as valid. An attacker who can get an application to verify tokens with an empty key, for example when a secret is read from an unset environment variable defaulting to an empty string, can forge tokens with arbitrary claims. The advisory states the issue was fixed in 1.9.1, so upgrade authlib to version 1.9.1 or later.

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
7.4	High	3.1	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.0030, the 22nd percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

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.