CVE catalog
CVE-2026-33128
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
- Severity
- High · CVSS 7.5
- Published
- Source
- [NVD] · [CVE record]
- EPSS
- 0.58% · Oct 25, 2026
A flaw was found in H3, a minimal HTTP framework. A remote attacker can exploit this flaw by injecting malicious Server-Sent Events (SSE) due to improper sanitization of newline characters in the `formatEventStreamMessage()` and `formatEventStreamComment()` functions. An attacker who controls any part of an SSE message field (id, event, data, or comment) can inject arbitrary SSE events to connected clients. Red Hat Product Security has determined that this vulnerability does not affect any currently supported Red Hat product. This assessment may evolve based on further analysis and discovery. For more information about this vulnerability and the products it affects, please see the linked references. The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Npm | h3 | Not reported | 2.0.1-rc.15 | fixed |
| Npm | h3 | Not reported | 1.15.6 | fixed |
| Cpe | h3 | Not reported | Not reported | unknown |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Npm | h3 | npm | Not reported | 2.0.1-rc.15 | Not reported | Not reported | Not reported |
| Npm | h3 | npm | Not reported | 1.15.6 | Not reported | Not reported | Not reported |
OpenFactory catalog packages
No matching packages in this catalog.
Observed:
References
- [https://github.com/advisories/GHSA-22cc-p3c6-wpvm]
- [https://nvd.nist.gov/vuln/detail/CVE-2026-33128]
- [https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33128.json]
[FIRST EPSS] · [GitHub Advisory Database] · [National Vulnerability Database (NVD)] · [Red Hat security advisories and VEX]