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Fencer Vulns
high 8.1

CVE-2023-42116 json

Exim SMTP Challenge Stack-based Buffer Overflow Remote Code Execution Vulnerability

published 2024-05-03 2 y ago modified 2026-06-17 4 mo ago also EUVD-2023-46575

cvss
8.1
version 3.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.8%
EPSS 3.8% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

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.

Patch / fix

  • Exim Exim 4.96.1, 4.97
  • exim4 Debian 12 4.96-15+deb12u2
  • exim4 Debian 14, Debian 13 4.97~RC1-2

debian advisories DEBIAN-CVE-2023-42116

  • exim4 Ubuntu 20.04 LTS 4.93-13ubuntu1.8
  • exim4 Ubuntu 22.04 LTS 4.95-4ubuntu2.3
  • exim4 Ubuntu Pro 14.04 LTS 4.82-3ubuntu2.4+esm6
  • exim4 Ubuntu Pro 16.04 LTS 4.86.2-2ubuntu2.6+esm4
  • exim4 Ubuntu Pro 18.04 LTS 4.90.1-1ubuntu1.10+esm1

ubuntu advisories UBUNTU-CVE-2023-42116

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • exim openSUSE Tumbleweed 4.96.1-1.1
  • exim Package Hub 15 SP5, openSUSE Leap 15.5 4.97.1-bp155.5.9.1
  • exim Package Hub 15 SP5, Package Hub 15 SP4, openSUSE Leap 15.5 +1 more 4.94.2-bp155.5.3.1

opensuse advisories openSUSE-SU-2024:13282-1openSUSE-SU-2024:0007-1openSUSE-SU-2023:0293-1

  • exim Alpine 3.24, Alpine 3.23, Alpine 3.22 +5 more 4.96.1-r0

alpine advisories ALPINE-CVE-2023-42116

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-42116 updated cvss 8.1

Exim: SMTP Challenge Stack-based Buffer Overflow Remote Code Execution Vulnerability

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
total
Assessed
2 y ago

Exploit prediction

3.79% chance of exploitation in the next 30 days, higher than 90% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.0 8.1 CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Exim Exim

Classification

Weakness
  • CWE-121 Stack-based Buffer Overflow

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.