eventsource-encoder vulnerable to SSE event injection via unsanitized `event` and `id` fields

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.0028, the 20th percentile, on 15 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

This record came from the full history of the GitHub Advisory Database, published 8 May 2026. New records show when each source confirmed them.

Sources

• GitHub Advisory Database: GHSA-m9g3-3g99-mhpx
• OSV: GHSA-m9g3-3g99-mhpx
• github.com/rexxars/eventsource-encoder/security/advisories/GHSA-m9g3-3g99-mhpx
• nvd.nist.gov/vuln/detail/CVE-2026-44214
• github.com/rexxars/eventsource-encoder
• html.spec.whatwg.org/multipage/server-sent-events.html#parsing-an-event-stream

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.