It was reported that the method used in the experimental DMARC code introduced in Exim 4.82 to parse the From header to determine the DMARC domain, used the expand_string() function to parse the raw data in the From header. This function recognizes various Exim expansion operations, which can be used to execute arbitrary code in the context of Exim and what features have been enabled at compile-time, including calling the embedded Perl interpreter (if enabled).
This flaw was introduced in Exim 4.82 and only if the EXPERIMENTAL_DMARC feature was enabled. It is fixed in Exim 4.82.1 by using internal parsing routines that are not subject to executing Exim's expansion functions. Prior versions of Exim are unaffected by this flaw as they did not include this experimental code.
This issue does NOT affect Exim as provided in Red Hat Enterprise Linux 5, EPEL 6, or any released version of Fedora.
Not vulnerable. This issue did not affect the versions of Exim as shipped with Red Hat Enterprise Linux 5 as they did not include the experimental DMARC support.