Goal Reached Thanks to every supporter — we hit 100%!

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-33128— h3 has a Server-Sent Events Injection via Unsanitized Newlines in Event Stream Fields

Quick assessment

Affected
h3js h3
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

H3是H3开源的一个HTTP框架。 H3 1.15.6之前版本和2.0.0至2.0.1-rc.14版本存在注入漏洞，该漏洞源于createEventStream缺少换行符清理，可能导致服务器发送事件注入。

CVSS 7.5 · High EPSS 0.69% · P51

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-33128

Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗

Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.

Vulnerability Title
h3 has a Server-Sent Events Injection via Unsanitized Newlines in Event Stream Fields
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对CRLF序列的转义处理不恰当(CRLF注入)
Source: CVE Program / CVE List V5
Vulnerability Title
H3 注入漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
H3是H3开源的一个HTTP框架。 H3 1.15.6之前版本和2.0.0至2.0.1-rc.14版本存在注入漏洞，该漏洞源于createEventStream缺少换行符清理，可能导致服务器发送事件注入。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
h3js h3 >= 2.0.0, < 2.0.1-rc.15 -

II. Public POCs for CVE-2026-33128

# POC Description Source Link Shenlong Link
AI-Generated POC Premium

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-33128

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-33128 (2)

Vendor Advisories for CVE-2026-33128 (1)

Same Patch Batch · h3js · 2026-03-20 · 3 CVEs total

CVE-2026-33131 7.4 HIGH h3 has a middleware bypass with one gadget
CVE-2026-33129 5.9 MEDIUM h3 has an observable timing discrepancy in basic auth utils

IV. Related Vulnerabilities

Same product: h3
Same vendor: h3js
Same weakness: CWE-93

V. Comments for CVE-2026-33128

No comments yet

Leave a comment