Vulnerability DatabaseCVE-2026-33128
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CVE-2026-33128
March 20, 2026
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 Packages
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v1.15.0 <v1.15.6
Fix Suggestion:
Update to version v1.15.6
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v0.0.1 <v2.0.1-rc.15
Fix Suggestion:
Update to version v2.0.1-rc.15
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v1.15.0 <v1.15.6
Fix Suggestion:
Update to version v1.15.6
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v0.0.1 <v2.0.1-rc.15
Fix Suggestion:
Update to version v2.0.1-rc.15
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v1.15.0 <v1.15.6
Fix Suggestion:
Update to version v1.15.6
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v0.0.1 <v2.0.1-rc.15
Fix Suggestion:
Update to version v2.0.1-rc.15
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v0.0.1 <v2.0.1-rc.15
Fix Suggestion:
Update to version v2.0.1-rc.15
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v0.0.1 <v2.0.1-rc.15
Fix Suggestion:
Update to version v2.0.1-rc.15
https://github.com/h3js/h3.git (GITHUB):
Affected version(s) >=v1.15.0 <v1.15.6
Fix Suggestion:
Update to version v1.15.6
h3 (NPM):
Affected version(s) >=2.0.0 <2.0.1-rc.15
Fix Suggestion:
Update to version 2.0.1-rc.15
h3 (NPM):
Affected version(s) >=2.0.0 <2.0.1-rc.15
Fix Suggestion:
Update to version 2.0.1-rc.15
h3 (NPM):
Affected version(s) >=0.2.0 <1.15.6
Fix Suggestion:
Update to version 1.15.6
h3 (NPM):
Affected version(s) >=0.2.0 <1.15.6
Fix Suggestion:
Update to version 1.15.6
h3 (NPM):
Affected version(s) >=0.2.0 <1.15.6
Fix Suggestion:
Update to version 1.15.6
h3 (NPM):
Affected version(s) >=2.0.0 <2.0.1-rc.15
Fix Suggestion:
Update to version 2.0.1-rc.15
h3 (NPM):
Affected version(s) >=0.2.0 <1.15.6
Fix Suggestion:
Update to version 1.15.6
h3 (NPM):
Affected version(s) >=2.0.0 <2.0.1-rc.15
Fix Suggestion:
Update to version 2.0.1-rc.15
h3 (NPM):
Affected version(s) >=0.2.0 <1.15.6
Fix Suggestion:
Update to version 1.15.6
Related Resources (5)
https://github.com/h3js/h3/blob/52c82e18bb643d124b8b9ec3b1f62b081f044611/src/utils/internal/event-stream.ts#L170-L187
https://github.com/h3js/h3/commit/7791538e15ca22437307c06b78fa155bb73632a6
https://nvd.nist.gov/vuln/detail/CVE-2026-33128
https://github.com/h3js/h3/security/advisories/GHSA-22cc-p3c6-wpvm
https://github.com/h3js/h3
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CVSS v4
Base Score:
9
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
HIGH
Vulnerable System Availability
NONE
Subsequent System Confidentiality
LOW
Subsequent System Integrity
HIGH
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality
LOW
Integrity
HIGH
Availability
NONE
Weakness Type (CWE)
Improper Neutralization of CRLF Sequences ('CRLF Injection')
CWE-93
EPSS
Base Score:
0.02