Vulnerability identifier: #VU81255

Vulnerability risk: Critical

CVSSv3.1: 8.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2023-42118

CWE-ID: CWE-191

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 integer underflow in libspf2 when parsing SPF macros. A remote attacker can pass specially crafted data to the server, trigger an integer underflow 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
http://www.zerodayinitiative.com/advisories/ZDI-23-1472/
http://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.