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OpenAdvisories
High · 7.5 CVE-2026-33128 EUVD-2026-13666GHSA-22cc-p3c6-wpvm

h3 has a Server-Sent Events Injection via Unsanitized Newlines in Event Stream Fields

Published Mar 20, 2026 · Updated Mar 20, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
h3js h3 >= 2.0.0, < 2.0.1-rc.15, < 1.15.6 —

Affected packages

EcosystemPackageAffectedFixedRecord
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 GHSA-22cc-p3c6-wpvm

References