CRLF Injection Affecting sse-channel package, versions <4.0.1
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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Test your applications- Snyk IDSNYK-JS-SSECHANNEL-16624719
- published10 May 2026
- disclosed5 May 2026
- creditSnailSploit
Introduced: 5 May 2026
NewCVE-2026-44217 (opens in a new tab)How to fix?
Upgrade sse-channel to version 4.0.1 or higher.
Overview
sse-channel is a Server-Sent Events "channel" where all messages are broadcasted to all connected clients, history is maintained automatically and server attempts to keep clients alive by sending "keep-alive" packets automatically.
Affected versions of this package are vulnerable to CRLF Injection via unsanitized event, retry, or id fields. An attacker can inject arbitrary messages into the SSE stream by supplying specially crafted input, potentially causing event spoofing, client-side manipulation, and data integrity issues.
Workaround
This vulnerability can be mitigated by sanitizing user input before passing it to the relevant fields, specifically by stripping any newlines.