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.
Published: 2026-05-26
Score: 5.8 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

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
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'}


Subscriptions

Rexxars Eventsource-encoder
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: 2026-06-17T10:50:22.090

Link: CVE-2026-44214

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

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

Weaknesses