CVE-2026-33128

HIGH

7.5

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.

CVE Details

CVSS v3.1 Score7.5

SeverityHIGH

CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N

Attack VectorNETWORK

ComplexityHIGH

Privileges RequiredNONE

User InteractionNONE

Published3/20/2026

Last Modified3/20/2026

Sourcenvd

Honeypot Sightings0

Affected Products

h3:h3

Weaknesses (CWE)

CWE-93

References

https://github.com/h3js/h3/blob/52c82e18bb643d124b8b9ec3b1f62b081f044611/src/utils/internal/event-stream.ts#L170-L187(security-advisories@github.com)

https://github.com/h3js/h3/commit/7791538e15ca22437307c06b78fa155bb73632a6(security-advisories@github.com)

https://github.com/h3js/h3/security/advisories/GHSA-22cc-p3c6-wpvm(security-advisories@github.com)

IOC Correlations

No correlations recorded

This product uses data from the NVD API but is not endorsed or certified by the NVD.