Cyber Posture

CVE-2025-25062

MediumPublic PoC

Published: 03 February 2025

Published
03 February 2025
Modified
23 January 2026
KEV Added
Patch
CVSS Score 4.4 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N
EPSS Score 0.2841 96.5th percentile
Risk Priority 26 60% EPSS · 20% KEV · 20% CVSS

Description

An adversary may steal web application or service session cookies and use them to gain access to web applications or Internet services as an authenticated user without needing credentials.

Security Summary

CVE-2025-25062 is a stored cross-site scripting (XSS) vulnerability, classified under CWE-79, affecting Backdrop CMS versions 1.28.x prior to 1.28.5 and 1.29.x prior to 1.29.3. The issue arises in the CKEditor 5 rich text editor module, where long text content is not sufficiently isolated, allowing attackers to inject specialized HTML and JavaScript. It has a CVSS v3.1 base score of 4.4 (AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N), indicating medium severity with network accessibility but high attack complexity, low privileges required, user interaction needed, and changed scope for limited confidentiality and integrity impacts.

An authenticated attacker with low privileges, such as the ability to create long text content via node or comment forms, can exploit this by embedding malicious payloads. The payload executes only when an administrator edits—rather than merely views—the affected content, potentially leading to theft of admin session data or manipulation of the admin's browser context. Exploitation requires the CKEditor 5 module to be enabled and relies on the admin's interaction.

The official Backdrop CMS security advisory (backdrop-sa-core-2025-001) recommends upgrading to Backdrop CMS 1.28.5 or 1.29.3 to mitigate the vulnerability. Additional details on the issue, including proof-of-concept exploitation, are available in third-party analyses such as those on Medium and GetAstra.

Details

CWE(s)
CWE-79

Affected Products

backdropcms
backdrop cms
1.28.0 — 1.28.5 · 1.29.0 — 1.29.3

MITRE ATT&CK Enterprise Techniques

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
T1185 Browser Session Hijacking Collection
Adversaries may take advantage of security vulnerabilities and inherent functionality in browser software to change content, modify user-behaviors, and intercept information as part of various browser session hijacking techniques.
T1539 Steal Web Session Cookie Credential Access
An adversary may steal web application or service session cookies and use them to gain access to web applications or Internet services as an authenticated user without needing credentials.
Why these techniques?

Stored XSS in web app enables exploitation of public-facing application (T1190) to inject JS that runs in admin browser, directly facilitating browser session hijacking (T1185) and theft of web session cookies (T1539) as described.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

References