CVE-2023-42116

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.

CVSS v3.1 Score

9.8

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weakness Type (CWE)

CWE-121 CWE-121

Affected Products

Vendor	Product	Versions
exim	exim	< 4.96.1

References

Other References

https://www.zerodayinitiative.com/advisories/ZDI-23-1470/ https://lists.debian.org/debian-lts-announce/2023/10/msg00002.html https://www.zerodayinitiative.com/advisories/ZDI-23-1470/

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. It has a CVSS v3.1 base score of 9.8 (CRITICAL).

How severe is CVE-2023-42116? +

CVE-2023-42116 has a CVSS v3.1 score of 9.8 out of 10, rated CRITICAL. This is a critical vulnerability that should be patched immediately.

What products are affected by CVE-2023-42116? +

CVE-2023-42116 affects products from exim, specifically: exim. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2023-42116? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-6239

A stack‑based buffer overflow vulnerability exists in Tapo C520WS v2 in the ONVIF CreateUsers service, where the device fails to …

CVE-2026-8356

LibreOffice can import presentations in the legacy binary PPT format. A stack buffer overflow existed when importing a colour-replacement record. …

CVE-2026-40489

editorconfig-core-c is an EditorConfig core library for use by plugins supporting EditorConfig parsing. Versions up to and including 0.12.10 have …

CVE-2025-26382

Under certain circumstances the iSTAR Configuration Utility (ICU) tool could have a buffer overflow issue

CVE-2025-1533

A stack buffer overflow has been identified in the AsIO3.sys driver. This vulnerability can be triggered by input manipulation, may …

CVE-2025-3916

CWE-121: Stack-based Buffer Overflow vulnerability exists that could cause local attackers being able to exploit these issues to potentially execute …