# CVE-2026-90927: filebrowser through 2.63.23 Denial of Service via unbounded WebSocket message

> Authenticated attackers can exhaust server memory by sending oversized WebSocket messages to the command handler, causing denial of service.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 16 Sep 2026
- **Also known as:** GHSA-39cx-23x9-5c8p, GHSA-9f2h-f5v4-r5qq

## What is CVE-2026-90927?

CVE-2026-90927 is a high-severity denial of service vulnerability in filebrowser, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

filebrowser through 2.63.23 fails to limit WebSocket message size in the /api/command handler before checking permissions, allowing authenticated users to buffer arbitrarily large messages. Attackers can send oversized WebSocket messages to exhaust server heap memory and cause denial of service regardless of EnableExec setting or Execute permission.

Weakness: CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-90927?


## How do I fix CVE-2026-90927?

No fix has been published for CVE-2026-90927 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-90927 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-90927 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90927 and fix it if it is affected.

What it is: CVE-2026-90927 is a high-severity denial of service vulnerability in filebrowser, published on 14 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-90927 exists.

Affected product: filebrowser. 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-2026-90927/ (Markdown: https://insights.sbomify.com/CVE-2026-90927/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90927
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90927
- OSV: https://osv.dev/vulnerability/CVE-2026-90927

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90927/
Summaries are generated and may contain mistakes; the official description above is the record.