---
cve: "CVE-2025-66506"
severity: "HIGH"
cvss: 7.5
epss: "21%"
vendor: "sigstore"
kev: false
exploited: false
published: "2025-12-04 22:15:49"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-16T13:38:20+02:00"
---

# CVE-2025-66506

> 7.5 HIGH · 🧪 PoC

## Beschreibung

Fulcio is a free-to-use certificate authority for issuing code signing certificates for an OpenID Connect (OIDC) identity. Prior to 1.8.3, function identity.extractIssuerURL splits (via a call to strings.Split) its argument (which is untrusted data) on periods. As a result, in the face of a malicious request with an (invalid) OIDC identity token in the payload containing many period characters, a call to extractIssuerURL incurs allocations to the tune of O(n) bytes (where n stands for the length of the function's argument), with a constant factor of about 16. This vulnerability is fixed in 1.8.3.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Keine | good |
| A Verfügbarkeit | Hoch | bad |

## Patch verfügbar (OSV)

- 3622f6e62cf74ff1477422a8c3aad4ca338ed047 (Commit)
- 765a0e57608b9ef390e1eeeea8595b9054c63a5a (Commit)

## Referenzen

- <https://github.com/sigstore/fulcio/security/advisories/GHSA-f83f-xpx7-ffpw>
- <https://github.com/sigstore/fulcio/commit/765a0e57608b9ef390e1eeeea8595b9054c63a5a>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2025-66506) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_