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CVE-2026-33128

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CVE-2026-33128

Published: Mar 20, 2026

Modified: Mar 20, 2026

PUBLISHED

CVSS v3.1

7.5

HIGH

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.

VendorProductVersions

h3js

h3

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

Weaknesses (CWE)

CWE-93

CVSS v3.1 Details

CVSS v3.1 Vector

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

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

Low

Integrity

High

Availability

None

References

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