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Advisory record · GHSA-f83f-xpx7-ffpw

Fulcio allocates excessive memory during token parsing

CVSS 7.5 HighEPSS 0.0023 · 13th percentile

Published by the GitHub Advisory Database at 5 Dec 2025, 18:18 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
github.com/sigstore/fulcioGo<1.8.31.8.3
Identifiers
GHSA-f83f-xpx7-ffpw · CVE-2025-66506 · GO-2025-4193
Weakness (CWE)
CWE-405
Tags
Published
5 Dec 2025
Updated
10 Sept 2026

Machine-written summary

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

Fulcio, the Go package github.com/sigstore/fulcio before 1.8.3, allocates excessive memory when parsing an invalid OIDC identity token containing many period characters. An attacker who can send a malicious request can cause large memory allocations, which is a resource-consumption denial of service. Upgrade to version 1.8.3 or later.

Written 1 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
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 0.0023, the 13th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:13 UTC First seen by agentprime
  2. 31 Oct 2026, 14:13 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.