How severe is CVE-2023-42116?

CVE-2023-42116 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-2023-42116 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-42116?

CVE-2023-42116 affects Exim. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-42116?

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-2023-42116 have an EU (EUVD) identifier?

Yes. CVE-2023-42116 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-46575.

When was CVE-2023-42116 published?

CVE-2023-42116 was published on 2024-05-03 and last updated on 2026-06-17.

CVE-2023-42116

CVE-2023-42116 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-121.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 3% (86th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2023-46575
Weakness: CWE-121
Affected product: Exim
Published: 2024-05-03
Last modified: 2026-06-17

Description

Exim SMTP Challenge Stack-based Buffer Overflow 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 handling of NTLM challenge requests. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17515.

Frequently asked questions

What is CVE-2023-42116?: Exim SMTP Challenge Stack-based Buffer Overflow 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 handling of NTLM challenge requests. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17515.
How severe is CVE-2023-42116?: CVE-2023-42116 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-2023-42116 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-42116?: CVE-2023-42116 affects Exim. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-42116?: 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-2023-42116 have an EU (EUVD) identifier?: Yes. CVE-2023-42116 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2023-46575.
When was CVE-2023-42116 published?: CVE-2023-42116 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

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CVE-2026-12846 — Critical (CVSS 10.0): GV-I/O Box 4E is a smart embedded device with 4 input and 4 relays output that can be controlled over Ethernet and…
CVE-2026-12485 — Critical (CVSS 10.0): GV-I/O Box 4E is a smart embedded device with 4 input and 4 relays output that can be controlled over Ethernet and…
CVE-2026-37541 — Critical (CVSS 10.0): Buffer overflow vulnerability in Open Vehicle Monitoring System 3 (OVMS3) 3.3.005. In canformat_gvret.cpp, the length…
CVE-2026-42996 — Critical (CVSS 10.0): JS8Call through 2.3.1 and JS8Call-improved before 3.0 have a stack-based buffer overflow via a radio transmission of…

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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)