P5Verified

CVE-2025-5266: firefox before 128.11.0 (exclusive), before 139.0 (exclusive)

CVE-2025-5266. CVSS 3.1 base score 4.3 (MEDIUM, Source advisory). EPSS 0.00327 (percentile 0.23479), scored 04-Oct-2026.

Affected technology

firefox · before 128.11.0 (exclusive)
mozilla

firefox · before 139.0 (exclusive)
mozilla

Component: Not specified by the source

Attack conditions (Source advisory, CVSS 3.1): Network (remote) · No privileges required · User interaction required

What an attacker can do

Source advisory’s CVSS 3.1 assessment (base score 4.3/10) rates confidentiality impact as low; integrity and availability impact as none. The description does not specify what an attacker can achieve beyond these rated impacts.

Published 12-Oct-2026 00:35 UTC

CWE: CWE-200
CCR priority: 17.3 /100 (P5)
CVSS 3.1: 4.3 /10 · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N · Source advisory
EPSS: 0.00327 · percentile 0.23825 · 2026-10-11
KEV: no

Provenance

FIRST EPSS daily exploit-probability · Source record · observed 2026-10-11 23:42:05.235979+00:00 UTC
NVD CVE API 2.0 · Source record · observed 2026-10-05 23:09:08.830529+00:00 UTC

Stable permalink: https://cybercodered.org/item/cve-cve-2025-5266.html