How severe is CVE-2026-54464?

No CVSS score has been assigned to CVE-2026-54464 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-54464?

CVE-2026-54464 affects the following packages: websocket-driver (RubyGems). Ecosystems affected: RubyGems.

How do I fix CVE-2026-54464?

Update websocket-driver to 0.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54464 is resolved across your whole dependency graph.

How do I detect CVE-2026-54464 in my RubyGems dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for websocket-driver, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-54464 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-54464 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-54464 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-54464?

CVE-2026-54464 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 39th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-54464?

CVE-2026-54464 is classified as CWE-770 (CWE-770). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-54464 published, and has it been updated?

CVE-2026-54464 was published on July 17, 2026 and was last updated on October 28, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💎 RubyGems

Not in CISA KEV

CVE-2026-54464 — websocket-driver

Fix: faye/websocket-driver-ruby@fa86417

CVE-2026-54464 is a CWE-770 vulnerability in websocket-driver. A fix is available for websocket-driver — see the affected versions and patch details below.

websocket-driver: Resource limit bypass via message compression

Also known asGHSA-33ph-fccm-39pj

Published

Jul 17, 2026

Updated

Oct 28, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54464.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs39th percentile — riskier than 39% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

💎websocket-driver

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💎RubyGems	`websocket-driver`	all versions	0.8.1`bundle update websocket-driver --conservative`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for websocket-driver, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update websocket-driver to 0.8.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54464 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

CVE-2026-54464 is a moderate-severity denial-of-service flaw in the websocket-driver RubyGem (CWE-131). When the permessage-deflate extension is enabled, the library enforces the configured maximum message size against the compressed frame length rather than the decompressed size, allowing a remote attacker to send…

Workaround published by Red Hat

Exploitation requires the permessage-deflate WebSocket extension to be enabled. Disabling permessage-deflate, or enforcing a strict maximum message size after decompression at the application layer, prevents exploitation. Upgrading the websocket-driver gem to 0.8.1 or later fully remediates the flaw.

Source: Red Hat security advisory for CVE-2026-54464 (CC BY 4.0)

Frequently Asked Questions

### 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 b

O3 Security · Impact-Aware SCA

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