CVE-2026-44214

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

MEDIUM
5.3
CVSS Score
Published: May 26, 2026 at 07:34 PM UTC
Updated: July 24, 2026 at 11:23 AM UTC
1 product affected across 1 vendorEventsource Encoder

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Severity
MEDIUM5.3
Exploit prediction
EPSS 0.3%
SSVC
PoC

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 1.0.2
Affected range stops below 1.0.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (1)

x_refsource_CONFIRMExploitMitigationVendor Advisory
Source: cverecord
https://github.com/rexxars/eventsource-encoder/security/advisories/GHSA-m9g3-3g99-mhpx

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-93CWE-113

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