CVE-2026-54464

MEDIUMCVSS 6.3/10EPSS 0.45%

Last modified

CVE-2026-54464 is a medium-severity vulnerability rated 6.3/10 on the CVSS scale. ### 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. EPSS estimates a 0.45% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 4.0
6.3/10

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS Probability
0.45%

36.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
fayewebsocket-driver-ruby< 0.8.1

References

Timeline

Published
Last Modified
Status
Deferred

Frequently Asked Questions

What is CVE-2026-54464?
### 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.
How severe is CVE-2026-54464?
CVE-2026-54464 has a CVSS score of 6.3/10 (MEDIUM severity). The EPSS model estimates a 0.45% probability of exploitation in the next 30 days.
How do I fix CVE-2026-54464?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST