CVE-2026-49975

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.

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
apache2	26.04 LTS resolute	Fixed 2.4.66-2ubuntu2.2
	25.10 questing	Fixed 2.4.64-1ubuntu3.5
	24.04 LTS noble	Fixed 2.4.58-1ubuntu8.13
	22.04 LTS jammy	Fixed 2.4.52-1ubuntu4.21
	20.04 LTS focal	Fixed 2.4.41-4ubuntu3.23+esm5
	18.04 LTS bionic	Fixed 2.4.29-1ubuntu4.27+esm10
	16.04 LTS xenial	Fixed 2.4.18-2ubuntu3.17+esm19
	14.04 LTS trusty	Not affected
nginx	26.04 LTS resolute	Fixed 1.28.3-2ubuntu1.5
	25.10 questing	Fixed 1.28.0-6ubuntu1.7
	24.04 LTS noble	Fixed 1.24.0-2ubuntu7.12
	22.04 LTS jammy	Fixed 1.18.0-6ubuntu14.15
	20.04 LTS focal	Vulnerable
	18.04 LTS bionic	Vulnerable
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

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Notes

mdeslaur

nginx fixed this by releasing 1.29.8 with a max_headers directive with a default of 1000. They did not mention this release on their security page, and did not assign an nginx specific CVE to this issue. The nginx fix for this issue breaks ABI and introduced a regression causing nginx to crash when being used with external modules. The CVE fix was reverted in 8398-2. USN-8398-3 provided a complete fix for this issue.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
apache2	Upstream: 35c6e40 Upstream: 47d3100
nginx	Upstream: 3656941

Severity score breakdown

CVSS version: CVSS v3.0

Base score 7.5 · High

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	None
Integrity impact	None
Availability impact	High

Scores

Parameter	Value
Base score	7.5 · High
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

USN-8384-1
Apache HTTP Server vulnerability
4 June 2026

USN-8398-1
nginx vulnerability
8 June 2026

USN-8398-3
nginx vulnerability
15 June 2026

USN-8398-4
nginx vulnerability
2 July 2026

USN-8571-1
Apache HTTP Server vulnerabilities
20 July 2026