How severe is CVE-2023-42117?

CVE-2023-42117 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2023-42117 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-42117?

CVE-2023-42117 affects Exim. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-42117?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

Does CVE-2023-42117 have an EU (EUVD) identifier?

Yes. CVE-2023-42117 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-46576.

When was CVE-2023-42117 published?

CVE-2023-42117 was published on 2024-05-03 and last updated on 2026-06-17.

CVE-2023-42117

CVE-2023-42117 is a critical-severity vulnerability in Exim with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-138.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 6% (92nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2023-46576
Weakness: CWE-138
Affected product: Exim
Published: 2024-05-03
Last modified: 2026-06-17

Description

Exim Improper Neutralization of Special Elements Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability. The specific flaw exists within the smtp service, which listens on TCP port 25 by default. The issue results from the lack of proper validation of user-supplied data, which can result in a memory corruption condition. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-17554.

Frequently asked questions

What is CVE-2023-42117?: Exim Improper Neutralization of Special Elements Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability. The specific flaw exists within the smtp service, which listens on TCP port 25 by default. The issue results from the lack of proper validation of user-supplied data, which can result in a memory corruption condition. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-17554.
How severe is CVE-2023-42117?: CVE-2023-42117 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2023-42117 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 6% (92nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-42117?: CVE-2023-42117 affects Exim. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-42117?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2023-42117 have an EU (EUVD) identifier?: Yes. CVE-2023-42117 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-46576.
When was CVE-2023-42117 published?: CVE-2023-42117 was published on 2024-05-03 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:exim:exim:*:*:*:*:*:*:*:*

More vulnerabilities in Exim

CVE-2026-45185 — Critical (CVSS 9.8): Exim before 4.99.3, in certain GnuTLS configurations, has a remotely reachable use-after-free in the BDAT body parsing…
CVE-2023-42116 — Critical (CVSS 9.8): Exim SMTP Challenge Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote…
CVE-2023-42115 — Critical (CVSS 9.8): Exim AUTH Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to…
CVE-2022-37452 — Critical (CVSS 9.8): Exim before 4.95 has a heap-based buffer overflow for the alias list in host_name_lookup in host.c when…
CVE-2020-28026 — Critical (CVSS 9.8): Exim 4 before 4.94.2 has Improper Neutralization of Line Delimiters, relevant in non-default configurations that enable…
CVE-2020-28024 — Critical (CVSS 9.8): Exim 4 before 4.94.2 allows Buffer Underwrite that may result in unauthenticated remote attackers executing arbitrary…

All CVEs affecting Exim →

Other CWE-138 vulnerabilities

CVE-2024-38133 — High (CVSS 7.8): Windows Kernel Elevation of Privilege Vulnerability
CVE-2026-26129 — High (CVSS 7.5): Improper neutralization of special elements used in a command ('command injection') in M365 Copilot allows an…
CVE-2026-32178 — High (CVSS 7.5): Improper neutralization of special elements in .NET allows an unauthorized attacker to perform spoofing over a network.
CVE-2022-0024 — High (CVSS 7.2): A vulnerability exists in Palo Alto Networks PAN-OS software that enables an authenticated network-based PAN-OS…
CVE-2026-20009 — Medium (CVSS 5.3): A vulnerability in the implementation of the proprietary SSH stack with SSH key-based authentication in Cisco Secure…
CVE-2024-51500 — Medium (CVSS 5.3): Meshtastic firmware is a device firmware for the Meshtastic project. The Meshtastic firmware does not check for packets…

Browse all CWE-138 vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

193.202.11.112 (ipv4-addr)
76.12.128.249 (ipv4-addr)
50.116.72.139 (ipv4-addr)
166.62.41.190 (ipv4-addr)
160.187.147.124 (ipv4-addr)
132.148.155.138 (ipv4-addr)
77.221.151.241 (ipv4-addr)
37.221.254.200 (ipv4-addr)