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EximApplication

CVE-2023-42114

MEDIUM · 5.3 CVSS v3.1 Published 2024-05-03
Fix available
A fix is available. Upgrade to 4.96.1 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
Exim NTLM Challenge Out-Of-Bounds Read Information Disclosure Vulnerability. This vulnerability allows remote attackers to disclose sensitive information 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 user-supplied data, which can result in a read past the end of an allocated data structure. An attacker can leverage this vulnerability to disclose information in the context of the service account. . Was ZDI-CAN-17433.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

This is an out-of-bounds read vulnerability in Exim's NTLM challenge handling. The lack of proper validation of user-supplied data during NTLM authentication allows an attacker to read memory beyond allocated buffer boundaries, potentially disclosing sensitive information from the service account's memory space.

MitigationUpdate Exim to the latest version containing the security patch. As a workaround, if NTLM authentication is not required, disable it in the Exim configuration. Monitor for any unusual memory disclosure patterns in logs.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
EximApplication
Affected:< 4.96.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check Exim version
    Run 'exim --version' or 'exim -v' to display the installed Exim version number
    Affected if The reported version is lower than 4.96.1 (for example, 4.95, 4.90, etc.)
  2. Locate Exim configuration file
    Find the main Exim configuration file, typically at /etc/exim/exim.conf, /etc/exim4/exim4.conf, or as specified in your system
    Affected if The configuration file exists and NTLM authenticators are defined
  3. Verify NTLM authenticator is enabled
    Search the Exim configuration for 'ntlm' or 'NTLM' within authenticator blocks (look for 'authenticator { ... }' sections)
    Affected if An authenticator named 'ntlm' or containing 'ntlm' driver is present and not commented out
  4. Confirm NTLM is advertised to clients
    Examine if the NTLM authenticator is actually active (not disabled via 'disabled = true') and check for 'mechanisms' setting containing 'NTLM'
    Affected if NTLM authentication is actively configured and available for incoming connections

Your environment is affected if the installed Exim version is below 4.96.1 AND NTLM authentication is enabled in the Exim configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 4.96.1 or later
Fixed in 4.96.1
Interim mitigation

Update Exim to the latest version containing the security patch. As a workaround, if NTLM authentication is not required, disable it in the Exim configuration. Monitor for any unusual memory disclosure patterns in logs.

Recommended fix High confidence

Exim 4.96.1 or later

  1. Check current Exim version using: exim -v -bV
  2. Plan maintenance window for the upgrade
  3. For Debian/Ubuntu: Run 'apt-get update && apt-get install exim4' or 'apt-get update && apt-get install exim4-daemon-light'
  4. For Red Hat/CentOS: Run 'yum update exim' or 'dnf update exim'
  5. For source compilation: Download Exim 4.96.1 or later from exim.org, compile with 'make', then 'make install'
  6. After upgrade, verify new version with: exim -bV
  7. Ensure NTLM authentication is properly configured if used, or consider disabling it if not required

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Exim Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
6.0 hours of engineering $1,060
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,696.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-42114 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data