CVE-2026-86252

h3 versions before 1.15.9 fail to sanitize carriage return characters in EventStream data and comment fields, allowing attackers to inject arbitrary SSE events by including unsanitized carriage returns. Attackers can inject event type directives, split single push calls into multiple browser-parsed events, or escape comment fields to inject data, bypassing the prior CVE fix that only addressed newline injection.

CVSS v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact LOW

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/h3js/h3/security/advisories/GHSA-4hxc-9384-m385
https://www.vulncheck.com/advisories/h3-before-1.15.9-sse-event-injection-via-carriage-return
https://github.com/h3js/h3/security/advisories/GHSA-4hxc-9384-m385

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-06 12:17

Updated : 2026-09-08 20:00

NVD link : CVE-2026-86252

Mitre link : CVE-2026-86252

CVE.ORG link : CVE-2026-86252

JSON object : View

Products Affected

No product.

CWE

CWE-74

Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

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