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

Goal: 1000 CNY · Raised: 1359 CNY

100%
Buy Us a Coffee

CVE-2026-69210— Http4s: WebSocket decoder accepts negative length, causing infinite decode loop

Quick assessment

Affected
http4s http4s
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.

http4s是http4s组织开源的一个Scala的HTTP服务框架。 http4s 0.23.35之前版本和1.0.0-M1至1.0.0-M47之前版本存在安全漏洞，该漏洞源于WebSocket FrameTranscoder.bodyLength允许负数64位长度，远程客户端通过Ember服务器完成WebSocket握手后可发送此类帧，导致解码器返回空帧且不推进输入，解码循环无限运行，占用CPU并无限增长ArrayBuffer，造成拒绝服务。

CVSS 7.5 · High EPSS 0.63% · P50

Affected Version Matrix 2

VendorProduct Version RangeStatus
http4s http4s < 0.23.35 affected
>= 1.0.0-M1, < 1.0.0-M47 affected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-69210

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Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.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
Http4s: WebSocket decoder accepts negative length, causing infinite decode loop
Source: CVE Program / CVE List V5
Vulnerability Description
Http4s is a Scala interface for HTTP services. Prior to 0.23.35 and 1.0.0-M47, WebSocket FrameTranscoder.bodyLength rejects extended payload lengths above Integer.MAX_VALUE but permits negative 64-bit lengths. A remote client that completes a WebSocket handshake through an Ember server can send such a frame, causing the decoder to return an empty frame without advancing its input. The decode loop then runs indefinitely, pins a worker at full CPU, and grows an ArrayBuffer without bound, resulting in denial of service. This issue is fixed in versions 0.23.35 and 1.0.0-M47.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
不可达退出条件的循环(无限循环)
Source: CVE Program / CVE List V5
Vulnerability Title
http4s 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
http4s是http4s组织开源的一个Scala的HTTP服务框架。 http4s 0.23.35之前版本和1.0.0-M1至1.0.0-M47之前版本存在安全漏洞，该漏洞源于WebSocket FrameTranscoder.bodyLength允许负数64位长度，远程客户端通过Ember服务器完成WebSocket握手后可发送此类帧，导致解码器返回空帧且不推进输入，解码循环无限运行，占用CPU并无限增长ArrayBuffer，造成拒绝服务。
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
http4s http4s < 0.23.35 -

II. Public POCs for CVE-2026-69210

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

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-69210

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-69210 (1)

Vendor Advisories for CVE-2026-69210 (1)

Vendor Pages for CVE-2026-69210 (2)

Same Patch Batch · http4s · 2026-09-15 · 18 CVEs total

CVE-2026-69204 9.2 CRITICAL Http4s: Ember accepts Transfer-Encoding combined with Content-Length (CL.TE request smuggl
CVE-2026-69217 8.7 HIGH Http4s: Ember Server accepts duplicate Content-Length headers
CVE-2026-69205 8.7 HIGH Http4s: Ember Transfer-Encoding value parsing (TE.CL / TE.0 request smuggling)
CVE-2026-69208 7.5 HIGH Http4s: DigestAuth nonce map grows unbounded
CVE-2026-88975 7.5 HIGH Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME
CVE-2026-69202 7.5 HIGH Http4s Ember HTTP/2: unbounded inbound body buffering
CVE-2026-69218 7.5 HIGH Http4s Ember HTTP/2: unbounded continuation frame accumulation
CVE-2026-69213 7.5 HIGH Http4s Ember HTTP/2: unbounded outbound frame queue
CVE-2026-69203 7.5 HIGH Http4s Ember HTTP/2: does not enforce SETTINGS_MAX_CONCURRENT_STREAMS
CVE-2026-69209 7.5 HIGH Http4s: WebSocket decoder accepts unbounded message sizes
CVE-2026-69214 6.8 MEDIUM Http4s: CookieJar middleware accepts arbitrary Set-Cookie domain
CVE-2026-69215 6.8 MEDIUM Http4s: CookieJar middleware matches by substring, leaking cookies cross-origin
CVE-2026-69201 5.9 MEDIUM Http4s: ResourceService and Webjar Service path escape via percent-encoded separators
CVE-2026-69212 5.9 MEDIUM Http4s: FollowRedirect middleware leaks credentials over https->http same-authority redire
CVE-2026-69206 5.9 MEDIUM Http4s: DigestAuth allows replay of captured requests
CVE-2026-69216 5.4 MEDIUM Http4s: Ember chunk parser lenience (TE.TE request smuggling)
CVE-2026-69211 4.8 MEDIUM Http4s: Set-Cookie rendering does not escape attribute delimiters

IV. Related Vulnerabilities

Same product: http4s
Same vendor: http4s
Same weakness: CWE-835