CVE-2016-1531 Exim MTA Privilege Escalation Vulnerability

Version Git tag
Exim 4.84.2 exim-4_84_2
Exim 4.85.2 exim-4_85_2
Exim 4.86.2 exim-4_86_2
Exim 4.87 RC 5 exim-4_87_RC5

(It's an updated version of 4.8{4,5,6}.1, fixing minor portability
issues for *BSD and OS/X).

The known download area contains packed tarballs. The tarballs for fixed
older versions (4.84.2, 4.85.2) are below the old/ directory.

Every tarball and the relevant commits and tags are signed with my GPG
key (as used for signing this mail).

Security fix for CVE-2016-1531

All installations having Exim set-uid root and using 'perl_startup' are
vulnerable to a local privilege escalation. Any user who can start an
instance of Exim (and this is normally *any* user) can gain root
privileges. If you do not use 'perl_startup' you *should* be safe.

New options

We had to introduce two new configuration options:

keep_environment =
add_environment =

Both options are empty per default. That is, Exim cleans the complete
environment on startup. This affects Exim itself and any subprocesses,
as transports, that may call other programs via some alias mechanisms,
as routers (queryprogram), lookups, and so on. This may affect used
libraries (e.g. LDAP).

** THIS MAY BREAK your existing installation **

If both options are not used in the configuration, Exim issues a warning
on startup. This warning disappears if at least one of these options is
used (even if set to an empty value).

keep_environment should contain a list of trusted environment variables.
(Do you trust PATH?). This may be a list of names and REs.

keep_environment = ^LDAP_ : FOO_PATH

To add (or override) variables, you can use add_environment:

add_environment = <; PATH=/sbin:/usr/sbin New behaviour ------------- Now Exim changes it's working directory to / right after startup, even before reading it's configuration. (Later Exim changes it's working directory to $spool_directory, as usual.) Exim only accepts an absolute configuration file path now, when using the -C option. Thank you for your understanding. Best regards from Dresden/Germany Viele Grüße aus Dresden Heiko Schlittermann -- ---------------------------- internet & unix support - Heiko Schlittermann, Dipl.-Ing. (TU) - {fon,fax}: +49.351.802998{1,3} - gnupg encrypted messages are welcome --------------- key ID: F69376CE - ! key id 7CBF764A and 972EAC9F are revoked since 2015-01 ------------ - This message was posted to the following mailing lists: Exim-announce Mailing List Info | Nearby Messages <- [exim-dev] Update on maintenance branch exim-4_86+fixes [c4dcf906ceb3] Tahini and Hummus Development Archives administrated by Hummus Admins Lurker (version 2.3)