Several vulnerabilities were discovered in the shadow suite of login
tools. An attacker may escalate privileges in specific configurations.
Shadow incorrectly lists pts/0 and pts/1 as physical terminals in
/etc/securetty. This allows local users to login as password-less
users even if they are connected by non-physical means such as SSH
(hence bypassing PAM's nullok_secure configuration). This notably
affects environments such as virtual machines automatically
generated with a default blank root password, allowing all local
users to escalate privileges. It should be noted however that
/etc/securetty will be dropped in Debian 11/bullseye.
The newusers tool could be made to manipulate internal data
structures in ways unintended by the authors. Malformed input may
lead to crashes (with a buffer overflow or other memory
corruption) or other unspecified behaviors. This crosses a
privilege boundary in, for example, certain web-hosting
environments in which a Control Panel allows an unprivileged user
account to create subaccounts.
For Debian 9 stretch, these problems have been fixed in version
We recommend that you upgrade your shadow packages.
For the detailed security status of shadow please refer to
its security tracker page at:
Further information about Debian LTS security advisories, how to apply
these updates to your system and frequently asked questions can be
found at: https://wiki.debian.org/LTS
Debian LTS Advisory DLA-2596-1 [email protected]
https://www.debian.org/lts/security/ Sylvain Beucler
March 17, 2021 https://wiki.debian.org/LTS
Version : 1:4.4-4.1+deb9u1