# 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.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:X`)
- **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 available:** No
- **Published:** 13 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-4mhr-77m9-cfv9

## 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.

Weakness: CWE-94 (Improper Control of Generation of Code), CWE-79 (Improper Neutralization of Input During Web Page Generation)

## 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.

## Is CVE-2026-90583 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-90583 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90583 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-90583 exists.

Affected product: kagisearch smallweb. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-90583/ (Markdown: https://insights.sbomify.com/CVE-2026-90583/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90583
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90583
- OSV: https://osv.dev/vulnerability/CVE-2026-90583

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90583/
Summaries are generated and may contain mistakes; the official description above is the record.