TI-2023-22486 Aliases CVE-2023-42118 GHSA-2vq7-8vvf-w66v

Integer underflow in Exim libspf2

MEDIUM 51CWE-191Published 2024-05-03 · Updated 2025-03-28

Key facts

Attack vector: Adjacent network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Code execution
Confidentiality · integrity · availability: High · High · High
Fix status: No fix listed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-191 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.08351 94th percentileScored 2026-11-07

Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Exim	libspf2	exim 4.96-RC0-14-24b8ed847-XX	—	No fix listed	CNA

libspf2 VendorExim Affected exim 4.96-RC0-14-24b8ed847-XX Fixed in — No fix listed CNA

CPE configurations NVD · 2

CPE	Versions	Role	Vendor
cpe:2.3:a:libspf2_project:libspf2:-:::::::*	not specified by NVD	Vulnerable	Libspf2 Project
cpe:2.3:a:exim:exim:-:::::::*	not specified by NVD	Running on	Exim

cpe:2.3:a:libspf2_project:libspf2:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Libspf2 Project
cpe:2.3:a:exim:exim:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Exim

Remediation

No fixed version listed by the sources yet.

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product

Red Hat

Timeline

2026-10-02 Threatist record created from CVE-2023-42118
2026-10-03 Alias added: GHSA-2vq7-8vvf-w66v
2026-10-04 Priority changed: HIGH → MEDIUM
2026-10-16 EPSS moved to the 90th–95th percentile
2026-11-04 EPSS moved to the 95th–99th percentile
2026-11-06 EPSS moved to the 90th–95th percentile

References

Advisory 1

ZDI-23-1472

TI-2019-12627 Exim 4.92 through 4.92.2 allows remote code execution, a different vulnerability than… KEVCVSS 3.1CRITICAL 9.8
TI-2019-07471 OS command injection in exim KEVCVSS 3.1CRITICAL 9.8
TI-2018-04965 An issue was discovered in the base64d function in the SMTP listener in Exim before… KEVCVSS 3.1CRITICAL 9.8
TI-2010-04077 Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70… KEVCVSS 3.1CRITICAL 9.8
TI-2010-04078 Exim 4.72 and earlier allows local users to gain privileges by leveraging the ability of… KEVCVSS 3.1HIGH 7.8
TI-2025-19707 SQL injection in Exim CVSS 3.1CRITICAL 9.8

See all 70 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences