This vulnerability allows network-adjacent attackers to disclose sensitive
information on affected installations of Exim. Authentication is not required
to
exploit this vulnerability.

The specific flaw exists within the smtp service, which listens on TCP port 25
by default. The issue results from the lack of proper validation of
user-supplied data, which can result in a read past the end of an allocated
buffer. An attacker can leverage this in conjunction with other vulnerabilities
to execute arbitrary code in the context of the service account.

06/22/22 – ZDI reported the vulnerability to the vendor.

04/25/23 – ZDI asked for an update.

04/25/23 – The vendor asked us to re-send the reports.

05/10/23 – ZDI sent the vulnerability to the vendor.

09/25/23 – ZDI asked for an update and informed the vendor that we intend to
publish the case as a zero-day advisory on 09/27/23.

-- Mitigation: Given the nature of the vulnerability, the only salient
mitigation strategy is to restrict interaction with the application.

References:
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2023-42119