CVE-2026-43924

What it is

FOSSBilling is a free, open-source billing and client management system. Prior to version 0.8.0, the Redirect module does not validate the URL scheme of administrator-configured destination URLs before storing or issuing redirects. This allows arbitrary external URLs to be configured as redirect targets, creating an open redirect vulnerability exploitable for phishing attacks. Users following a legitimate FOSSBilling URL can be silently redirected to an attacker-controlled external site. The redirect is issued as a 301 (Moved Permanently) response, which browsers cache persistently, amplifying the impact. Exploitation requires administrator privileges to create or modify redirect entries, limiting practical attack scenarios to multi-admin environments or compromised admin accounts. Version 0.8.0 fixes the issue. Some workarounds are available. Restrict admin access to the Redirect module to trusted administrators only and/or audit existing redirect entries in the database (the `extension_meta` table with `extension = 'mod_redirect'`) for any unexpected or external target URLs.

At a glance

Exploitability

Can be exploited over the network with an admin-level account, but needs a user to act. Limited direct impact.

Exploit odds

0.3% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-06-03 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-07-22 20:10 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.3% in the next 30 days (EPSS).
• Severity: 4.8 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-06-03 20:16 UTC

Last modified

2026-07-22 20:10 UTC

Exploit probability

0.3% · EPSS, next 30 days

Weakness

CWE-601

Record status

Deferred

Attack profile CVSS 4.0 · 4.8

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

High

User interaction

Passive

Confidentiality

None

Integrity

None

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-43924.md and follow it. Check whether this project is affected by CVE-2026-43924. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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