CVE-2025-66458 Lookyloo has multiple XSS due to unsafe use of f-strings in Markup
Attacker can execute arbitrary JavaScript via malicious JSON responses, affecting Lookyloo users.
- 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-2025-66458?
CVE-2025-66458 is a medium-severity cross-site scripting vulnerability in lookyloo, published on 2 Dec 2025. 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
Lookyloo is a web interface that allows users to capture a website page and then display a tree of domains that call each other. Prior to 1.35.3, there are multiple XSS due to unsafe use of f-strings in Markup. The issue requires a malicious 3rd party server responding with a JSON document containing JS code in a script element. This vulnerability is fixed in 1.35.3.
Weakness: CWE-79
Which versions are affected by CVE-2025-66458?
It affects 1 product.
Products include Lookyloo Lookyloo.
How do I fix CVE-2025-66458?
No fix has been published for CVE-2025-66458 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-2025-66458 being exploited?
There is no known exploitation of CVE-2025-66458 in the wild and no public exploit code.
Other vulnerabilities in lookyloo
Sources
Also known as GHSA-58h2-652v-gq87.