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Date: Wed, 05 Feb 2020 11:31:55 -0500
From: "Larry W. Cashdollar" <>
To: Open Security <>
Subject: Re: CVE-2019-18901: mariadb: possible symlink attack
 for the mysql user in the SUSE specific mysql-systemd-helper script

Hello Matthias,

That chmod 640 might be interesting if applied to /etc/shadow.  It could allow some users to read the password hashes.

On 2/5/20, 7:46 AM, "Matthias Gerstner" <> wrote:

    Hello list,
    in the course of a review of the mariadb packaging in the SUSE Linux
    distribution I discovered that a SUSE specific helper script
    "mysql-systemd-helper" unsafely operates with root privileges in
    the /var/lib/mysql directory [1].
    During initial package installation and during upgrade scenarios the
    file /var/lib/mysql/mysql_upgrade_info is created/overwritten and
    modified using the following shell commands:
    echo -n "$MYSQLVER" > "$datadir"/mysql_upgrade_info
    chmod 640 "$datadir/mysql_upgrade_info"
    Since the unprivileged mysql user owns the parent directory it can
    remove this file and replace it with a symlink to write/overwrite in
    privileged file systems locations. This could mostly be used for
    denial-of-service purposes, a full privilege escalation should not be
    easily achieved by this vulnerability, since the file content cannot be
    controlled by a potential attacker.
    Future SUSE mariadb packages will keep this file in a safe location in
    /var/lib/misc. Older, still supported packages will be fixed soon.
    Matthias Gerstner <>
    Dipl.-Wirtsch.-Inf. (FH), Security Engineer
    Phone: +49 911 740 53 290
    GPG Key ID: 0x14C405C971923553
    SUSE Software Solutions Germany GmbH
    HRB 36809, AG Nürnberg
    Geschäftsführer: Felix Imendörffer

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