CVE-2023-42118: exim Integer Underflow (CVSS 8.8)

Description

Exim libspf2 Integer Underflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of Exim libspf2. Authentication is not required to exploit this vulnerability. The specific flaw exists within the parsing of SPF macros. When parsing SPF macros, the process does not properly validate user-supplied data, which can result in an integer underflow before writing to memory. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17578.

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CVSS v3.1 Score

8.8

HIGH

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-191 CWE-191

Affected Products

Vendor	Product	Versions
libspf2_project	libspf2	All
exim	exim	All

References

Other References

https://www.zerodayinitiative.com/advisories/ZDI-23-1472/ http://www.openwall.com/lists/oss-security/2025/03/28/1 https://www.zerodayinitiative.com/advisories/ZDI-23-1472/

Frequently Asked Questions

What is CVE-2023-42118? +

Exim libspf2 Integer Underflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of Exim libspf2. Authentication is not required to exploit this vulnerability. The specific flaw exists within the parsing of SPF macros. When parsing SPF macros, the process does not properly validate user-supplied data, which can result in an integer underflow before writing to memory. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17578. It has a CVSS v3.1 base score of 8.8 (HIGH).

How severe is CVE-2023-42118? +

CVE-2023-42118 has a CVSS v3.1 score of 8.8 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching.

What products are affected by CVE-2023-42118? +

CVE-2023-42118 affects products from exim, libspf2_project, specifically: exim, libspf2. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2023-42118? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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