HTTP Response Splitting Affecting eventsource-encoder package, versions <1.0.2
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-EVENTSOURCEENCODER-16691315
- published14 May 2026
- disclosed8 May 2026
- creditUnknown
Introduced: 8 May 2026
NewCVE-2026-44214 (opens in a new tab)How to fix?
Upgrade eventsource-encoder to version 1.0.2 or higher.
Overview
eventsource-encoder is an Encodes events as well-formed EventSource/Server Sent Event (SSE) messages
Affected versions of this package are vulnerable to HTTP Response Splitting via unsanitized event and id fields in the encoding process. An attacker can inject arbitrary Server-Sent Events line terminators and forge additional SSE fields or entire messages on the stream by supplying specially crafted input to these fields. This is only exploitable if untrusted input is passed into the event or id fields of a message.
Workaround
This vulnerability can be mitigated by validating or stripping line terminators from any untrusted value before passing it to the encoder.