Description
eventsource-encoder encodes events as well-formed EventSource/Server Sent Event (SSE) messages. Prior to 1.0.2, eventsource-encoder does not sanitize the event or id fields of an EventSourceMessage before serializing them. An attacker who controls either field can inject arbitrary Server-Sent Events line terminators (\n, \r, or \r\n) and thereby forge additional SSE fields or entire messages on the stream. This vulnerability is fixed in 1.0.2.
Affected products
rexxars: eventsource-encoder
References2
- github.com/rexxars/eventsource-encoder/security/advisories/GHSA… ExploitMitigationVendor Advisory
- github.com/rexxars/eventsource-encoder/security/advisories/GHSA… ExploitMitigationVendor Advisory
Metrics
- CVSS 3.1
-
5.3
MEDIUM
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - EPSS — exploit probability
- 0% percentile: 20 · as of 14 November 2026
- CWE
- CWE-93CWE-113
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