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

Goal: 1000 CNY · Raised: 1336 CNY

100%
Buy Us a Coffee

CVE-2026-90678

Quick assessment

Affected
HAProxy HAProxy
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.

以下是该漏洞描述的中文翻译： 在 HAProxy 3.3.0 至 3.4.4 版本以及 3.5-dev1 至 3.5-dev5 版本中发现了问题。利用该漏洞需要满足以下前提条件：HAProxy 必须启用 QUIC 支持并配置了 QUIC 绑定监听器，且受影响的流量必须通过复用的连接以 HTTP/1.1 协议和分块传输编码（chunked transfer coding）到达后端。在上述条件下，当携带的 HTTP/3 请求没有 头时，HTTP/3 多路复用器会在解码数据帧头时，将该头中声明的长度计入流端点的“已知输入

CVSS 7.5 · High

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-2026-90678

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Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.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
N/A
Source: CVE Program / CVE List V5
Vulnerability Description
An issue was discovered in HAProxy 3.3.0 through 3.4.4 and in 3.5-dev1 through 3.5-dev5. Exploitation requires an HTTP/3 frontend: HAProxy must be built with QUIC support and configured with a QUIC bind listener, and the affected traffic must reach a backend over HTTP/1.1 using chunked transfer coding on a reused connection. Under those conditions, when an HTTP/3 request carries no Content-Length header, the HTTP/3 multiplexer credits the length declared in a DATA frame header to the stream endpoint's known-input-payload estimate at the moment the frame header is decoded, before the payload has been received, and that declared length is emitted verbatim as the HTTP/1.1 chunk size. A remote unauthenticated client that declares more payload than it delivers and then ends the stream causes HAProxy to announce a chunk larger than the bytes it writes and to return the connection to the idle pool in a desynchronized state. The result is potential HTTP request smuggling on reused backend connections: an attacker can place a request past a frontend rule such as a path-based http-request deny, so that the smuggled request is never seen by HAProxy's HTTP analysis, and can cause concurrent clients' requests, including their request lines and Authorization headers, to be consumed as the attacker's request body and lost. Exploitation is not deterministic; it depends on a race with backend connection pooling, succeeding in a majority of but not all trials during testing, and can be retried freely. The mechanism was introduced in 3.3-dev10; releases 3.2.x and earlier are unaffected.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
长度参数不一致性处理不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
HAProxy HAProxy 3.3.0 ~ 3.3.14 -

II. Public POCs for CVE-2026-90678

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

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-90678

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-90678 (2)

Other References for CVE-2026-90678 (1)

IV. Related Vulnerabilities

Same product: HAProxy
Same vendor: HAProxy
Same weakness: CWE-130

V. Comments for CVE-2026-90678

No comments yet

Leave a comment