vulnerability: rewrite arbitrary user file

[Vasily Kulikov]

Binary package hint: feh

Hi, I've just discovered that feh is vulnerable to rewriting any user file:

      tmpname_timestamper =
         estrjoin("", "/tmp/feh_", cppid, "_", basename, NULL);
...
            execlp("wget", "wget", "-N", "-O", tmpname_timestamper, newurl,
                   quiet, (char*) NULL);

If attacker knows PID of feh and knows the URL, it can create the link to any user file. wget would overwrite it.

Thanks.

[Kees Cook (kees)]

Thanks for taking the time to report this bug and helping to make Ubuntu better.

The latest release of Ubuntu is not vulnerable to symlink race attack, but earlier release will need fixing. https://wiki.ubuntu.com/Security/Features#symlink

Since the package referred to in this bug is in universe or multiverse, it is community maintained. If you are able, I suggest posting a debdiff for this issue. When a debdiff is available, members of the security team will review it and publish the package. See the following link for more information: https://wiki.ubuntu.com/SecurityTeam/UpdateProcedures