Medium 5.8Published May 26, 2026

CVE-2026-44214eventsource-encoder: SSE event injection via unsanitized event and id fields

Updated under an hour ago (Oct 28, 2026, 2:50 AM ET)

Does this affect you?

It affects rexxars eventsource-encoder and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for rexxars eventsource-encoder

Exploited in the last 30 days

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.

CVSS: 5.8 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Weakness (CWE): CWE-93, CWE-113
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: May 27, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

rexxars eventsource-encoder rexxars:eventsource_encoder (from the name)	before 1.0.2	CNA record
rexxars eventsource-encoder rexxars:eventsource-encoder	before 1.0.2	NVD

References

References

https://github.com/rexxars/eventsource-encoder/security/advisories/GHSA-m9g3-3g99-mhpx	x-refsource-confirm, exploit, mitigation, vendor-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.