CVE-2025-66506: fulcio before 1.8.3 (exclusive), < 1.8.3

CVE-2025-66506. CVSS 3.1 base score 7.5 (HIGH, Vendor/CNA). EPSS 0.00211 (percentile 0.10646), scored 17-Oct-2026.

Affected technology

fulcio · before 1.8.3 (exclusive)
linuxfoundation

fulcio · < 1.8.3
sigstore

Component: Not specified by the source
Function: identity.extractIssuerURL

Attack conditions (Vendor/CNA, CVSS 3.1): Network (remote) · No privileges required · No user interaction required

What an attacker can do

Vendor/CNA’s CVSS 3.1 assessment (base score 7.5/10) rates confidentiality and integrity impact as none; availability impact as high. The description does not specify what an attacker can achieve beyond these rated impacts.

Published 18-Oct-2026 15:50 UTC

CWE: CWE-405
CCR priority: 30.1 /100 (P4)
CVSS 3.1: 7.5 /10 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H · Vendor/CNA
EPSS: 0.00211 · percentile 0.10646 · 2026-10-17
KEV: no

Provenance

NVD CVE API 2.0 · Source record · observed 2026-10-18 15:50:37.644431+00:00 UTC

Stable permalink: https://cybercodered.org/item/cve-cve-2025-66506.html