CVE-2026-54490: websocket-driver: Resource limit bypass via message compression
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 0.7.5, 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.
Other sources
websocket-driver is a WebSocket protocol handler with pluggable I/O. Prior to 0.7.5, if this library is used 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 because the limit is checked against the message frames' length headers, which give the size of the compressed data, not the size after decompression in lib/websocket/driver/hybi.js. This can lead to applications accepting larger messages than expected and exceeding their intended resource usage. This issue is fixed in version 0.7.5.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
npm/websocket-driverto a version that resolves this vulnerability.Fixed in 0.7.5 - Upgrade
Upgrade
websocket-driverto a version that resolves this vulnerability.Fixed in 0.7.5 - Compensating control
If websocket-driver is used with the permessage-deflate extension, ensure your WebSocket server/client enforces the intended maximum message size after decompression (mitigates the pre-0.7.5 behavior where the limit is checked against compressed frame length headers in lib/websocket/driver/hybi.js).
Event History
Frequently Asked Questions
What is the severity of CVE-2026-54490?
The severity of CVE-2026-54490 is classified as medium with a score of 6.3.
What is the impact of CVE-2026-54490?
CVE-2026-54490 allows a WebSocket server or client to accept messages larger than the configured maximum message size due to a resource limit bypass when using the 'permessage-deflate' extension.
How do I fix CVE-2026-54490?
To fix CVE-2026-54490, upgrade to the latest version of the websocket-driver library that addresses this vulnerability.
What kind of applications are affected by CVE-2026-54490?
Applications utilizing the websocket-driver library with the 'permessage-deflate' extension are at risk of CVE-2026-54490.
When was CVE-2026-54490 published?
CVE-2026-54490 was published on July 15, 2026.