CVE-2026-90583 kagisearch smallweb Query String Rendering sw.py index cross site scripting
Remote attackers can execute arbitrary scripts via crafted query strings in smallweb, requiring raw HTTP requests to bypass browser encoding.
- 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-2026-90583?
CVE-2026-90583 is a medium-severity cross-site scripting vulnerability in kagisearch smallweb, published on 13 Sep 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 security flaw has been discovered in kagisearch smallweb up to 0ecb9c48edbf98dc7e934b54fbac43869e64b4cf. The affected element is the function index of the file app/sw.py of the component Query String Rendering. Performing a manipulation of the argument qs results in cross site scripting. The attack is possible to be carried out remotely. This product adopts a rolling release strategy to maintain continuous delivery. Therefore, version details for affected or updated releases cannot be specified. The patch is named 00b68144e583f20a6b67e29cf01bc07f57979ffb. It is recommended to apply a patch to fix this issue. Exploitability requires a raw HTTP request carrying unencoded double-quote characters in the query string - Werkzeug's request.query_string returns the raw request-target, and ordinary browsers percent-encode " as %22, so the payload only lands via netcat/curl-style raw sockets.
Which versions are affected by CVE-2026-90583?
How do I fix CVE-2026-90583?
No fix has been published for CVE-2026-90583 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-2026-90583 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-90583 exists.
Sources
Also known as GHSA-4mhr-77m9-cfv9.