Allocation of Resources Without Limits or Throttling Affecting crossbar package, versions [,26.7.1)
Threat Intelligence
Snyk has a proof-of-concept or detailed explanation of how to exploit this vulnerability.
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-CROSSBAR-20046663
- published22 Sept 2026
- disclosed18 Sept 2026
- creditBrian
Introduced: 18 Sep 2026
NewCVE-2026-77528 (opens in a new tab)How to fix?
Upgrade crossbar to version 26.7.1 or higher.
Overview
crossbar is a Crossbar.io multi-protocol (WAMP/WebSocket, REST/HTTP, MQTT) application router for microservices.
Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling via the onFrameData function in protocol.py, where the maxMessagePayloadSize limit is enforced against the compressed wire size of a permessage-compressed WebSocket frame rather than the uncompressed (inflated) application-level payload. An attacker can send a small compressed WebSocket frame that inflates far beyond the configured limit, bypassing the size check and delivering an oversized payload to the application, which can crash or exhaust resources in the receiving process.