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.

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-m9g3-3g99-mhpx eventsource-encoder vulnerable to SSE event injection via unsanitized `event` and `id` fields
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 28 May 2026 14:30:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:rexxars:eventsource-encoder:*:*:*:*:*:node.js:*:*

Wed, 27 May 2026 14:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 27 May 2026 10:30:00 +0000

Type Values Removed Values Added
First Time appeared Rexxars
Rexxars eventsource-encoder
Vendors & Products Rexxars
Rexxars eventsource-encoder

Tue, 26 May 2026 19:45:00 +0000

Type Values Removed Values Added
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.
Title eventsource-encoder: SSE event injection via unsanitized event and id fields
Weaknesses CWE-113
CWE-93
References
Metrics cvssV3_1

{'score': 5.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-05-27T13:19:45.558Z

Reserved: 2026-05-05T15:13:47.572Z

Link: CVE-2026-44214

cve-icon Vulnrichment

Updated: 2026-05-27T13:19:39.824Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-26T20:16:19.803

Modified: 2026-05-28T14:30:02.060

Link: CVE-2026-44214

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-27T10:08:41Z

Weaknesses