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Date: Wed, 18 Oct 2017 12:55:21 +0000
From: Robert Watson <>
To:, Bastian Blank <>
Subject: Re: CVE-2017-8805: Unsafe symlinks not filtered in
 Debian mirror script ftpsync

Since security is determined by file and directory permissions and
ownership, not by symlinks, wouldn't the fact that a malicious user did not
have permissions to access the symlink's target file/directory prevent any

On Tue, Oct 17, 2017, 12:27 Bastian Blank <> wrote:

> Hi folks
> ftpsync is the tool we use to mirror Debian everywhere.  It uses rsync
> to do the heavy lifting.
> rsync can copy symlinks.  We enable this option, as the Debian tree
> includes symlinks in various of locations.  Unless a special option
> (--safe-links) is given, such symlinks can point to arbitrary locations,
> even outside of the mirror tree.
> An attacker with the ability to add symlinks to the upstream mirror can
> create symlinks to arbitrary files or even directories.  Depending on
> the config, a HTTP server will follow such symlinks.
> Upstream patch:
> ---------------
>   ->
> Regards,
> Bastian
> --
> Beam me up, Scotty!

Robert "DocSalvager" Watson
... trust in truth keeps hope alive

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