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CVE-2026-49975

Apache HTTP Server: mod_http2 denial of service

Published: Jun 8, 2026Updated: Jul 23, 2026 Sources: CVE List NVD BDUCWE-789
7.5HIGH
NVD MITRE
EPSS Score
28.0%
Top 2.1%
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
Patch Available
Self-Check
OpenVAS

Description

Memory Allocation with Excessive Size Value vulnerability in Apache HTTP Server's mod_http leads to denial of service via malicious HTTP requests. This issue affects Apache HTTP Server: from 2.4.17 through 2.4.67.

In plain language

AI Worth attention

CVE-2026-49975 is a denial-of-service weakness in Apache HTTP Server’s mod_http that can crash or seriously slow the server when it receives malicious requests; if you run Apache HTTP Server in the affected versions, you should act soon, but this is not confirmed as widely exploited yet.

What to do

  1. Update Apache HTTP Server to a version outside 2.4.17 through 2.4.67 (ask your IT person to apply the vendor patch). 2) If you can’t update immediately, ask your IT person to temporarily reduce exposure (for example, restrict direct access to the affected endpoint paths from the public internet). 3) If you’re behind a reverse proxy or CDN, confirm with your provider/IT team whether requests hitting the affected component are filtered or mitigated.

CVSS Vector Breakdown

AV:NAC:LPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High
Open in CVSS calculator →

Weaknesses

CWE-789CWE-409

Affected Products

Microsoft Corp
commercial·USaka microsoft corporation
Windows Server 2025On-premOS
Operating Systems / windows
Microsoft IISOn-premWeb App
Web & CMS Plugins
Cloudflare, Inc
commercial·USaka cloudflare inc
PingoraLibrary
OSS Libraries / generic-library
Apache Software Foundation
oss-project·USaka apache foundation
Apache HTTP ServerOn-premWeb App
Networking Infrastructure / load-balancer-proxy
NGINX Inc.
commercial·USaka nginx, njs, nginx plus
nginx
Networking Infrastructure
Сообщество свободного программного обеспечения
oss-projectaka fsf
EnvoyLibraryLibrary
OSS Libraries / web-framework
apache
oss-project·USaka apache httpd, apache http server
http serverOn-premWeb App
Networking Infrastructure / load-balancer-proxy
and 2 more affected products View all →

Exploitability

Official Patch Available
Is your org exposed to CVE-2026-49975?We can run the check for you — a free external exposure review, no install. Check my exposure

References

https://blog.calif.io/p/codex-discovered-a-hidden-http2-bomb
blog.calif.io
https://github.com/nginx/nginx/releases/tag/release-1.29.8
github.com
https://github.com/nginx/nginx/pull/1116
github.com
and 23 more references View all →
News mentions
7

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