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CVE-2026-44214

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

Published: May 26, 2026Updated: May 26, 2026 Sources: CVE List
NVD MITRE
5.8CVSS
MEDIUM

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:CC:NI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:CScope
Changed
Impact
C:NConfidentiality
None
I:LIntegrity
Low
A:NAvailability
None

Weaknesses

CWE-93CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')CWE-113CWE-113: Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')

Affected Products

eventsource-encoder
rexxars

Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

References

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

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