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Public proof of conceptFix available

CVE-2023-42115

A public proof of concept exists; no exploitation attested.

  • Published2024-05-03
  • Fixed in4.96.1 · 4.95
  • WeaknessCWE-787

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

Exim AUTH Out-Of-Bounds Write 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 write past the end of a buffer. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17434.

Timeline

dates in UTC
  1. 2024-05-0303:15CVE publishedNVD
  2. 2026-10-2319:23First public proof of conceptPoC-in-GitHub
  3. 2026-10-2319:23EPSS crossed 10 %FIRST EPSS

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2023-42115?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2023-42115?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · CISA-ADP
Exim
BranchAffectedFixed in
4.96< 4.96.14.96.1
4.95< 4.954.95

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Exim to 4.96.1 · 4.95

Detection

read 2026-10-23 19:23 UTC
Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
2 repositories, unverifiedkirinse/cve-2023-42115doaso/CVE-2023-42115
PoC-in-GitHub

Sources

  • NVDCVE recordread 2026-10-23
  • CISA-ADPSSVC decisionpoc2024-09-20
  • OpenCVESSVC decisionpoc—
  • CNACVSS 3.09.8read 2026-10-23
  • CNAweakness (CWE)CWE-787read 2026-10-23
  • FIRST EPSSEPSS score12.1 %read 2026-10-23
  • PoC-in-GitHubproof of concept2read 2026-10-23

Technical details

CVSS v3 Vector
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2024-05-03
Last Modified
2026-06-17
NVD status
Analyzed

Frequently asked questions

What is CVE-2023-42115?

Exim AUTH Out-Of-Bounds Write 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 write past the end of a buffer. An attacker can leverage this vulnerability to execute code in the context of the service account. . Was ZDI-CAN-17434.

Is CVE-2023-42115 actively exploited?

A proof-of-concept exploit exists for CVE-2023-42115, but active exploitation has not been confirmed at this time.

What is the CVSS score for CVE-2023-42115?

CVE-2023-42115 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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