#VU81252 Out-of-bounds write in Exim - CVE-2023-42115

Vulnerability identifier: #VU81252

Vulnerability risk: Critical

CVSSv4.0: 8.9 [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:P/U:Red]

CVE-ID: CVE-2023-42115

CWE-ID: CWE-787

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Exim
Server applications / Mail servers

Vendor: Exim

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a boundary error when handling AUTH command. A remote non-authenticated attacker can send specially crafted data to the server, trigger an out-of-bounds write 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-23-1469/
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. However, proof of concept for this vulnerability is available.