CVE-2026-44214

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

Published May 26, 2026 CVSS 3.1 · 5.8 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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

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

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
May 27, 2026, 1:19 PM
Reserved
May 5, 2026, 3:13 PM
Status
Analyzed
Published
May 26, 2026, 8:16 PM
Modified
Jul 24, 2026, 11:10 AM