CVE-2025-61599: Emlog Pro Stored XSS Vulnerability

CVE-2025-61599 Overview

CVE-2025-61599 is a stored Cross-Site Scripting (XSS) vulnerability in the Twitter feature of Emlog Pro version 2.5.21 and below. Emlog is an open source website building system used to publish blogs and lightweight sites. An authenticated user with permission to post a Twitter message can inject arbitrary JavaScript. The payload persists on the server and executes in the browser of any viewer, including administrators. The issue is tracked as [CWE-79] and currently has no vendor fix.

Critical Impact
Authenticated attackers can hijack administrator sessions, escalate privileges, and pivot to full site takeover through persistent JavaScript execution.

Affected Products

Emlog Pro 2.5.21
All prior Emlog Pro releases
CPE: cpe:2.3:a:emlog:emlog:*:*:*:*:pro:*:*:*

Discovery Timeline

2025-10-03 - CVE-2025-61599 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-61599

Vulnerability Analysis

The vulnerability resides in the Emlog Pro Twitter microblog feature. This feature allows authenticated users to publish short posts to the site. The application stores post content without sanitizing or encoding HTML and JavaScript. When any user, including administrators, opens the malicious post, the browser parses and executes the injected script in the site's origin. The classification [CWE-79] confirms improper neutralization of input during web page generation.

Execution in an administrator context enables session token theft, forced administrative actions through the site's own APIs, and creation of persistent backdoor accounts. Because the payload is stored, exploitation does not require social engineering beyond the victim viewing an existing post.

Root Cause

The root cause is missing output encoding on user-supplied content within the Twitter feature. Server-side handlers accept post bodies without stripping or escaping HTML tags and event handler attributes. Rendered pages inject the raw content into the DOM, allowing <script> tags and inline JavaScript handlers to execute.

Attack Vector

Exploitation requires network access to the Emlog Pro instance and an authenticated account with Twitter post privileges. The attacker submits a post containing a JavaScript payload through the standard posting interface. The malicious content persists in the database and executes each time an authenticated user renders the post. See the GitHub Security Advisory for additional technical detail.

Detection Methods for CVE-2025-61599

Indicators of Compromise

Stored Twitter posts containing <script> tags, javascript: URIs, or DOM event handlers such as onerror and onload.
Unexpected outbound HTTP requests from administrator browsers to attacker-controlled domains after viewing Twitter posts.
New administrator accounts or modified user roles created shortly after an admin session interacted with the Twitter feature.

Detection Strategies

Query the Emlog database for post records where the body field matches regex patterns for HTML tags, on*= handlers, or base64-encoded script payloads.
Inspect web server access logs for POST requests to the Twitter posting endpoint followed by administrator GET requests to the same post ID.
Deploy Content Security Policy (CSP) violation reporting to surface inline script execution on rendered post pages.

Monitoring Recommendations

Alert on administrator account creation, password resets, or plugin installation events that follow Twitter post views.
Monitor browser telemetry for anomalous XMLHttpRequest or fetch activity originating from Emlog admin sessions.
Track authentication cookie use from unexpected IP addresses to identify session hijacking that follows XSS execution.

How to Mitigate CVE-2025-61599

Immediate Actions Required

Restrict Twitter posting privileges to trusted administrator accounts until a patch is released.
Audit existing Twitter posts and remove any entries containing HTML tags or scripting constructs.
Enforce a strict Content Security Policy that blocks inline scripts on all Emlog-rendered pages.

Patch Information

No vendor fix is available at the time of publication. Monitor the Emlog GitHub Security Advisory GHSA-rm5c-mjpg-vm89 for updates and apply the patched release as soon as it is published.

Workarounds

Place the Emlog Pro instance behind a Web Application Firewall (WAF) with signatures that block XSS payloads targeting the Twitter endpoint.
Disable the Twitter feature entirely if it is not required for site operations.
Require administrators to review new Twitter posts using an isolated browser profile without cached authentication cookies.

bash

# Example WAF rule concept for blocking script tags in Twitter POST bodies
# (adapt to your WAF's rule syntax, e.g., ModSecurity CRS)
SecRule REQUEST_URI "@contains /admin/twitter" \
  "chain,deny,status:403,id:1006159,msg:'CVE-2025-61599 Emlog Twitter XSS'"
  SecRule REQUEST_BODY "@rx (?i)(<script|onerror=|onload=|javascript:)" "t:none"