CVE-2026-33128

CRITICAL EPSS 38.2%
Published Mar 20, 20263mo ago · Modified Jun 17, 20262w ago
10.0 CVSS 3.1
Critical
Find Similar
Published Mar 20, 2026 3mo ago
Last Modified Jun 17, 2026 2w ago

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.

CVSS Details

Base Score
10.0
Exploitability
3.9
Impact
6.0
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Changed
Confidentiality High
Integrity High
Availability High

Threat Intelligence

EPSS Exploit Probability
38.2% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 1

CWE-93

Affected Products 15

VendorProductVersionRange
h3h3* <1.15.6
h3h32.0.0any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any
h3h32.0.1any

References 3

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

Remediation

  • github.com https://github.com/h3js/h3/commit/7791538e15ca22437307c06b78fa155bb73632a6
    Patch