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

> Attackers can bypass message size limits in websocket-driver when using permessage-deflate, causing resource exhaustion and denial of service.

- **Severity:** Medium 6.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Jul 2026
- **Updated:** 21 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-54464, GHSA-33ph-fccm-39pj, MINI-6mvc-ggj8-2gj6, MINI-jmrm-8jmw-jgjq, UBUNTU-CVE-2026-54464

## What is CVE-2026-54464?

CVE-2026-54464 is a medium-severity denial of service vulnerability in faye websocket-driver-ruby, published on 17 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-54464?

2 open source packages ship an affected version, including websocket-driver.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `websocket-driver` | RubyGems | All versions | 0.8.1 |
| `websocket-driver` | RubyGems | All versions | 0.8.1 |

## How do I fix CVE-2026-54464?

Upgrade websocket-driver to 0.8.1 or later.

## Is CVE-2026-54464 being exploited?

There is no known exploitation of CVE-2026-54464 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-54464 and fix it if it is affected.

What it is: CVE-2026-54464 is a medium-severity denial of service vulnerability in faye websocket-driver-ruby, published on 17 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-54464 in the wild and no public exploit code.

Affected packages and fixed versions:
- websocket-driver (RubyGems): affected all versions; fixed in 0.8.1
- websocket-driver (RubyGems): affected all versions; fixed in 0.8.1

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-2026-54464/ (Markdown: https://insights.sbomify.com/CVE-2026-54464/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-54464
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-54464
- OSV: https://osv.dev/vulnerability/CVE-2026-54464

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-54464/
Summaries are generated and may contain mistakes; the official description above is the record.