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

Goal: 1000 CNY · Raised: 1336 CNY

100%
Buy Us a Coffee

CVE-2026-88975— Http4s: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE

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 是一个用于 HTTP 服务的 Scala 接口。在 0.23.37 和 1.0.0-M48 之前的版本中，Ember 的 HTTP/2 读取循环会解析数据帧声明的 24 位长度字段，但会在与 SETTINGS_MAX_FRAME_SIZE 进行比较之前，先缓冲整个负载数据。未认证的通信对端可以在 Ember 通告了 16 KiB 最大帧大小的连接上，声明一个接近 16 MiB 的负载，并选择一次性发送或缓慢流式传输该负载，从而在 能够拒绝该帧之前，导致每个连接最多可产生 1024 倍的内存放大效应。此

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 2

VendorProduct Version RangeStatus
http4s http4s < 0.23.37 affected
>= 1.0.0-M1, < 1.0.0-M48 affected
Get alerts for future matching vulnerabilities Log in to subscribe

I. Basic Information for CVE-2026-88975

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Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.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: Ember HTTP/2 buffers a frame's declared payload before checking SETTINGS_MAX_FRAME_SIZE
Source: CVE Program / CVE List V5
Vulnerability Description
Http4s is a Scala interface for HTTP services. Prior to 0.23.37 and 1.0.0-M48, Ember’s HTTP/2 read loop parses a frame’s 24-bit declared length but waits to buffer the entire payload before comparing it with SETTINGS_MAX_FRAME_SIZE. An unauthenticated peer can declare a payload near 16 MiB on a connection where Ember advertised 16 KiB and either complete or slowly stream it, causing up to 1024-fold memory amplification per connection before processFrame can reject the frame. The shared H2Connection.readLoop affects withHttp2 servers and clients, while HTTP/2-disabled configurations are unaffected, and the patch rejects oversized frames before buffering their payloads. This issue is fixed in versions 0.23.37 and 1.0.0-M48.
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
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
http4s http4s < 0.23.37 -

II. Public POCs for CVE-2026-88975

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

No public POC found.

Login to generate AI POC

III. Intelligence Information for CVE-2026-88975

请登录查看更多情报信息。

Patches & Fixes for CVE-2026-88975 (1)

Vendor Advisories for CVE-2026-88975 (2)

Vendor Pages for CVE-2026-88975 (1)

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-2026-69202 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-2026-69210 7.5 HIGH Http4s: WebSocket decoder accepts negative length, causing infinite decode loop
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-400

V. Comments for CVE-2026-88975

No comments yet

Leave a comment