#VU81253 Stack-based buffer overflow in Exim - CVE-2023-42116

Vulnerability identifier: #VU81253

Vulnerability risk: Critical

CVSSv4.0: 8.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Red]

CVE-ID: CVE-2023-42116

CWE-ID: CWE-121

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Exim
Server applications / Mail servers

Vendor: Exim

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to a boundary error when handling NTLM challenge requests. A remote unauthenticated attacker can send specially crafted data to the server, trigger a stack-based buffer overflow and execute arbitrary code on the target system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Exim: 4.00 - 4.96

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External links
https://www.zerodayinitiative.com/advisories/ZDI-23-1470/
https://www.exim.org/static/doc/security/CVE-2023-zdi.txt

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.