Cyber Resilience

CVE-2023-42118

Memory Safety in Libspf2 Project Libspf2

High EPSSMemory Safety
Published
03 May 2024
Modified
07 August 2025
CVSS Score v3.1 8.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS Score 0.52 99th percentile
Risk Priority 85 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-42118 is a high-severity Wrap or Wraparound (CWE-191) vulnerability in Libspf2 Project Libspf2. Its CVSS base score is 8.8 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 1% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.

EU & UK References

Vulnerability Data

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…

more

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.

CWE(s)
CWE-191

Related Threats

MITRE ATT&CK Enterprise Techniques

T1068 Exploitation for Privilege Escalation Privilege Escalation
Adversaries may exploit software vulnerabilities in an attempt to elevate privileges.
attack.mitre.org →
T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
T1203 Exploitation for Client Execution Execution
Adversaries may exploit software vulnerabilities in client applications to execute code.
attack.mitre.org →
T1210 Exploitation of Remote Services Lateral Movement
Adversaries may exploit remote services to gain unauthorized access to internal systems once inside of a network.
attack.mitre.org →
T1212 Exploitation for Credential Access Credential Access
Adversaries may exploit software vulnerabilities in an attempt to collect credentials.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2025-30232Same product: Exim Exim
CVE-2023-42116Same product: Exim Exim
CVE-2025-67896Same product: Exim Exim
CVE-2020-28018Same product: Exim Exim
CVE-2026-45185Same product: Exim Exim
CVE-2023-42119Same product: Exim Exim
CVE-2026-40686Same product: Exim Exim
CVE-2023-42114Same product: Exim Exim
CVE-2026-40685Same product: Exim Exim
CVE-2023-42115Same product: Exim Exim

Affected Assets

libspf2 project
libspf2
all versions

Mitigating Controls

Mitigating Controls (NIST 800-53 r5) AI

SA-11 Developer Testing and Evaluation good match

Developer testing and static/dynamic analysis directly find integer underflow defects before code is released.

SA-8 Security and Privacy Engineering Principles partial match

Security engineering principles require use of safe arithmetic constructs or language features that structurally eliminate integer underflow during subtraction.

SI-10 Information Input Validation partial match

Input validation can reject or sanitize values that would cause a subtraction to underflow the representable range.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.PS-06 full match
prevents

Secure SDLC practices directly prevent integer underflow defects via input validation, bounds checking, and static analysis.

ID.RA-01 partial match
prevents

Vulnerability scanning and code analysis can surface underflow flaws after they are introduced.

PR.PS-02 partial match
prevents

Routine patching can remediate known underflow bugs once they are discovered in deployed software.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing in development catches integer underflow defects before release.

A.8.25 Secure development life cycle partial match
prevents

Secure development lifecycle mandates input validation and arithmetic checks that prevent integer underflow.

A.8.26 Application security requirements partial match
prevents

Application security requirements include bounds checking and safe arithmetic to avoid underflow conditions.

A.8.27 Secure system architecture and engineering principles partial match
prevents

Secure architecture principles require defensive coding patterns that mitigate integer wraparound risks.

A.8.28 Secure coding partial match
prevents

Secure coding standards directly prescribe safe integer handling and overflow/underflow prevention.

References