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Vulnerability · Published May 3, 2024 · Assigned by zdi

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

High 7.5

In plain English

A high-severity security flaw in libspf2 from Exim. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 8.4% (higher than 95% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.0)7.5High
Exploit odds (30 days)8.4%top 5.0% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official 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 packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.20libspf21.2.11-r3ALPINE-CVE-2023-42118
Alpine:v3.21libspf21.2.11-r3ALPINE-CVE-2023-42118
Alpine:v3.22libspf21.2.11-r3ALPINE-CVE-2023-42118
Alpine:v3.23libspf21.2.11-r3ALPINE-CVE-2023-42118
Alpine:v3.24libspf21.2.11-r3ALPINE-CVE-2023-42118
Debian:12libspf2no fix listedDEBIAN-CVE-2023-42118
Debian:13libspf2no fix listedDEBIAN-CVE-2023-42118
Debian:14libspf2no fix listedDEBIAN-CVE-2023-42118
Ubuntu:22.04:LTSexim4no fix listedUBUNTU-CVE-2023-42118
Ubuntu:24.04:LTSexim4no fix listedUBUNTU-CVE-2023-42118
Ubuntu:25.10exim4no fix listedUBUNTU-CVE-2023-42118
Ubuntu:26.04:LTSexim4no fix listedUBUNTU-CVE-2023-42118
Ubuntu:26.10exim4no fix listedUBUNTU-CVE-2023-42118
Ubuntu:22.04:LTSlibspf2no fix listedUBUNTU-CVE-2023-42118
Ubuntu:24.04:LTSlibspf2no fix listedUBUNTU-CVE-2023-42118
Ubuntu:25.10libspf2no fix listedUBUNTU-CVE-2023-42118
Ubuntu:26.04:LTSlibspf2no fix listedUBUNTU-CVE-2023-42118
Ubuntu:26.10libspf2no fix listedUBUNTU-CVE-2023-42118

Affected products (as reported)

VendorProductVersions
Exim libspf2 exim 4.96-RC0-14-24b8ed847-XX

Weakness: CWE-191 · Vector: CVSS:3.0/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References