CVE-2026-33128

Summary

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.

Affected Software

VendorProductVersion RangeStatus
h3jsh3>= 2.0.0, < 2.0.1-rc.15affected
h3jsh3< 1.15.6affected

Weaknesses

  • CWE-93: CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection')

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: poc
    • Automatable: no
    • Technical Impact: partial

References