CVE-2026-6507

Publication date 17 April 2026

Last updated 22 May 2026

Ubuntu priority

Cvss 3 Severity Score

Description

A flaw was found in dnsmasq. A remote attacker could exploit an out-of-bounds write vulnerability by sending a specially crafted BOOTREPLY (Bootstrap Protocol Reply) packet to a dnsmasq server configured with the `--dhcp-split-relay` option. This can lead to memory corruption, causing the dnsmasq daemon to crash and resulting in a denial of service (DoS).

Read the notes from the security team

Status

Show unmaintained releases

Package	Ubuntu Release	Status
dnsmasq	26.04 LTS resolute	Vulnerable
	25.10 questing	Not affected
	24.04 LTS noble	Not affected
	22.04 LTS jammy	Not affected
	20.04 LTS focal	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

mdeslaur

introduced in 2.92test20 by: https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commitdiff;h=1677c6e10b81d4e1181e3a3f88e738ea6d69be8a

Patch details

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

Package	Patch details
dnsmasq	Upstream: https://thekelleys.org.uk/gitweb/?p=dnsmasq.git;a=commitdiff;h=9ad74926d4f7f34ff902e1db5235535aa813c33f

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H