Uncaught Exception Affecting org.webjars.npm:engine.io package, versions [6.6.0,6.6.10)
Threat Intelligence
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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- published13 Oct 2026
- disclosed29 Sept 2026
- creditThai Son Dinh
Introduced: 29 Sep 2026
NewCVE-2026-102599 (opens in a new tab)How to fix?
Upgrade org.webjars.npm:engine.io to version 6.6.10 or higher.
Overview
org.webjars.npm:engine.io is a WebJar for engine.io.
Affected versions of this package are vulnerable to Uncaught Exception via the session upgrade handler in server.ts, where follow-up requests and transport upgrades do not validate that the Engine.IO protocol revision matches the one negotiated during the initial handshake. An attacker can send an upgrade request with a mismatched or missing EIO query parameter, causing a transport using a different parser and heartbeat mode to attach to an existing session, which disrupts the session and results in a crash.