CVE-2026-33128

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

CVSS 7.5 HIGHEPSS 0.5%CWE-93

Vexday Risk Score

21Bajo

Decisión SSVC (CISA)

Track

Sin señal de explotación → monitorear

CVSS 7.5EPSS 0.5%KEV nãoPoC —Nuclei —Metasploit —Patch —

Ciclo de vida

20 mar 2026Publicada en NVD

Recomendación: Monitorear — sin señal de explotación por ahora.

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

Productos afectados

h3js · h3

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Referencias

https://github.com/h3js/h3/blob/52c82e18bb643d124b8b9ec3b1f62b081f044611/src/utils/internal/event-stream.ts#L170-L187 https://github.com/h3js/h3/commit/7791538e15ca22437307c06b78fa155bb73632a6 https://github.com/h3js/h3/security/advisories/GHSA-22cc-p3c6-wpvm