CVE-2026-66824 Stored Cross-Site Scripting via Unsafe Capture Tree JSON Embedding
Stored XSS in lookyloo allows attackers to execute arbitrary scripts in victims' browsers via crafted capture tree data, leading to session hijacking or data manipulation.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-66824?
CVE-2026-66824 is a critical cross-site scripting vulnerability in lookyloo, published on 27 Jul 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
A stored cross-site scripting vulnerability existed in the capture tree visualization page. The application embedded the serialized capture tree directly into an inline JavaScript block using the Jinja safe filter.
Because the tree data can contain values derived from captured and potentially attacker-controlled web content, a specially crafted value could prematurely terminate the surrounding <script> element and inject arbitrary HTML or JavaScript. The malicious code would execute in the browser of a user viewing the affected capture tree.
Successful exploitation could allow an attacker to perform actions using the victim’s authenticated session, access information available to the victim, or modify application data within the permissions of the affected user.
The patch removes the JSON data from the HTML document and retrieves it through a dedicated API endpoint. The client then processes the response using response.json(), preventing capture data from being interpreted as executable content within the original page’s HTML or JavaScript context.
Weakness: CWE-79
Which versions are affected by CVE-2026-66824?
How do I fix CVE-2026-66824?
No fix has been published for CVE-2026-66824 yet. Limit exposure of the affected software until one is available.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-66824 being exploited?
There is no known exploitation of CVE-2026-66824 in the wild and no public exploit code.
Sources
Also known as GHSA-vjmw-phg6-9f2x.