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Advisory record · GHSA-v3q9-2p3m-7g43

Token reuse in Ory fosite

CVSS 8.1 HighEPSS 0.0087 · 59th percentile

Published by the GitHub Advisory Database at 24 May 2021, 16:57 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/ory/fositeGo<0.31.00.31.0
Identifiers
GHSA-v3q9-2p3m-7g43 · CVE-2020-15222 · GO-2021-0110
Weakness (CWE)
CWE-287 · CWE-345
Tags
Published
24 May 2021
Updated
8 Jul 2026

Machine-written summary

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

The Go package github.com/ory/fosite is affected before version 0.31.0 when clients use the private_key_jwt client authentication method, because it does not check that the assertion's jti value is unique. An attacker who can obtain a valid client assertion can reuse it to request access tokens again, as the source demonstrates by obtaining two tokens from one assertion. Upgrade to fosite 0.31.0 or later. As a workaround, do not allow clients to use private_key_jwt.

Written 6 Nov 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

ScoreRatingCVSSVectorSource
8.1 High 3.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0087, the 59th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 15:05 UTC First seen by agentprime
  2. 31 Oct 2026, 15:05 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.