Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| H3 | H3 | < 1.15.6 |
Related Weaknesses (CWE)
References
- https://github.com/h3js/h3/blob/52c82e18bb643d124b8b9ec3b1f62b081f044611/src/utiProduct
- https://github.com/h3js/h3/commit/7791538e15ca22437307c06b78fa155bb73632a6Patch
- https://github.com/h3js/h3/security/advisories/GHSA-22cc-p3c6-wpvmExploitVendor Advisory
FAQ
What is CVE-2026-33128?
CVE-2026-33128 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 saniti...
How severe is CVE-2026-33128?
CVE-2026-33128 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-33128?
Check the references section above for vendor advisories and patch information. Affected products include: H3 H3.