CVE-2026-4408

Name	CVE-2026-4408
Description	A flaw was found in Samba. A remote attacker can exploit a misconfiguration in Samba file servers and classic domain controllers that use the "check password script" feature. If this script is configured with the %u substitution character, the client-controlled username is passed without proper escaping of shell meta-characters. This vulnerability allows an attacker to achieve remote command execution on the affected system. This issue primarily affects non-standard configurations where the "check password script" is used with %u and the samba-dcerpcd service is started as a system service.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
References	DSA-6297-1

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
samba (PTS)	bullseye	2:4.13.13+dfsg-1~deb11u6	vulnerable
	bullseye (security)	2:4.13.13+dfsg-1~deb11u7	vulnerable
	bookworm	2:4.17.12+dfsg-0+deb12u3	vulnerable
	bookworm (security)	2:4.17.12+dfsg-0+deb12u4	fixed
	trixie	2:4.22.8+dfsg-0+deb13u1	vulnerable
	trixie (security)	2:4.22.8+dfsg-0+deb13u2	fixed
	forky, sid	2:4.24.3+dfsg-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Origin
samba	source	bookworm	2:4.17.12+dfsg-0+deb12u4	DSA-6297-1
samba	source	trixie	2:4.22.8+dfsg-0+deb13u2	DSA-6297-1
samba	source	(unstable)	2:4.24.3+dfsg-1

https://www.samba.org/samba/security/CVE-2026-4408.html