Advisory Details

September 27th, 2023

(0Day) Exim Improper Neutralization of Special Elements Remote Code Execution Vulnerability

ZDI-23-1471
ZDI-CAN-17554

CVE ID CVE-2023-42117
CVSS SCORE 8.1, AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
AFFECTED VENDORS Exim
AFFECTED PRODUCTS Exim
VULNERABILITY DETAILS

This vulnerability allows remote attackers to execute arbitrary code 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 memory corruption condition. An attacker can leverage this vulnerability to execute code in the context of the current process.

ADDITIONAL DETAILS

06/06/22 – ZDI requested a PSIRT contact.

06/14/22 – 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.


DISCLOSURE TIMELINE
  • 2022-06-15 - Vulnerability reported to vendor
  • 2023-09-27 - Coordinated public release of advisory
CREDIT Anonymous
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