CVE-2026-88975Network attack vector

Remote denial of service via oversized frame buffering

Published Sep 15, 2026 · Updated Sep 15, 2026

Uncontrolled resource consumption in http4s Ember before 0.23.37 and 1.0.0-M48 allows remote attackers to exhaust process memory. H2Frame.RawFrame.fromByteVector reads the 24-bit length, and H2Connection.readLoop buffers 9 plus that length before processFrame enforces SETTINGS_MAX_FRAME_SIZE. The flaw is reachable without authentication only when Ember HTTP/2 is enabled; a peer can hold nearly 16 MiB per connection and interrupt service through memory exhaustion.

CVSS severity7.5
High
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uncontrolled resource consumption in http4s Ember before 0.23.37 and 1.0.0-M48 allows remote attackers to exhaust process memory. H2Frame.RawFrame.fromByteVector reads the 24-bit length, and H2Connection.readLoop buffers 9 plus that length before processFrame enforces SETTINGS_MAX_FRAME_SIZE. The flaw is reachable without authentication only when Ember HTTP/2 is enabled; a peer can hold nearly 16 MiB per connection and interrupt service through memory exhaustion.

The record

CVE
CVE-2026-88975
Published
Sep 15, 2026
Updated
Sep 15, 2026
Vendor
http4s
Product
http4s
Classifications
CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 15, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 15, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 0.23.37
  2. Affected versionversion=>= 1.0.0-M1, < 1.0.0-M48

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

http4s · http4sversion=< 0.23.37; version=>= 1.0.0-M1, < 1.0.0-M48

Published CVSS scores

7.5GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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