CVSS 3.1
10.0 criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:HCVE-2026-33128
Critical (10.0) in h3 h3. EPSS 0.6% chance of exploitation in the next 30 days. Fixed in h3 1.15.6, 2.0.1-rc.15.
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.
Severity
- EPSS
- 0.6% chance of exploitation in the next 30 days; higher than 47% of CVEs (scores of 2026-10-31)
- CWE
- CWE-93
- Published
- Modified
- Record from
- the NVD, synced
Affected
- h3:h3
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-22cc-p3c6-wpvm | npm | h3 | >=2.0.0 <2.0.1-rc.15 | 2.0.1-rc.15 |
| GHSA-22cc-p3c6-wpvm | npm | h3 | <1.15.6 | 1.15.6 |