|Description||In Shadow 4.13, it is possible to inject control characters into fields provided to the SUID program chfn (change finger). Although it is not possible to exploit this directly (e.g., adding a new user fails because \n is in the block list), it is possible to misrepresent the /etc/passwd file when viewed. Use of \r manipulations and Unicode characters to work around blocking of the : character make it possible to give the impression that a new user has been added. In other words, an adversary may be able to convince a system administrator to take the system offline (an indirect, social-engineered denial of service) by demonstrating that "cat /etc/passwd" shows a rogue user account.|
|Source||CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)|
Vulnerable and fixed packages
The table below lists information on source packages.
|sid, trixie, bookworm||1:4.13+dfsg1-1||vulnerable|
The information below is based on the following data on fixed versions.
|Package||Type||Release||Fixed Version||Urgency||Origin||Debian Bugs|
[bookworm] - shadow <no-dsa> (Minor issue)
[bullseye] - shadow <no-dsa> (Minor issue)
[buster] - shadow <no-dsa> (Minor issue)
Fixed by: https://github.com/shadow-maint/shadow/commit/e5905c4b84d4fb90aefcd96ee618411ebfac663d (4.14.0-rc1)