CVE-2026-33128
h3 has a Server-Sent Events Injection via Unsanitized Newlines in Event Stream Fields
- State
- Published
- Severity
- 7.5 High
- Published
- Mar 20, 2026
- Updated
- Mar 20, 2026
- Reserved
- Mar 17, 2026
Description
H3 is a minimal H(TTP) framework. In versions prior to 1.15.6 and between 2.0.0 through 2.0.1-rc.14, createEventStream is vulnerable to Server-Sent Events (SSE) injection due to missing newline sanitization in formatEventStreamMessage() and formatEventStreamComment(). An attacker who controls any part of an SSE message field (id, event, data, or comment) can inject arbitrary SSE events to connected clients. This issue is fixed in versions 1.15.6 and 2.0.1-rc.15.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N | GitHub_M |
Weaknesses
- CWE-93 Improper Neutralization of CRLF Sequences ('CRLF Injection')
Affected Products
| Product | Versions |
|---|---|
h3h3js |
|
References
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