What’s Vulnerable › Vulnerabilities

CVE-2023-42118: Exim libspf2 Integer Underflow Remote Code Execution Vulnerability

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 8.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2024-05-03 · updated 2026-06-17
• Weakness: CWE-191

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.

Affected products

• Exim libspf2: all versions

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/

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