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EximApplication

CVE-2020-28014

MEDIUM · 6.1 CVSS v3.1 Published 2021-05-06
Fix available
A fix is available. Upgrade to 4.94.2 or later.
See remediation →
63/100
Remediation priority · Elevated
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 4 before 4.94.2 allows Execution with Unnecessary Privileges. The -oP option is available to the exim user, and allows a denial of service because root-owned files can be overwritten.

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

Exim versions before 4.94.2 allow the unprivileged exim user to invoke the -oP (preserve file permissions) option, which should require root privileges. This misconfiguration permits the exim user to overwrite root-owned files, enabling denial of service by corrupting critical system files.

MitigationUpgrade Exim to version 4.94.2 or later to obtain the patched binary that restricts -oP usage to privileged users only.

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:>= 4.00, < 4.94.2

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
High

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

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. Identify installed Exim version
    Run 'exim --version' or check the package manager (dpkg -l exim, rpm -q exim)
    Affected if The version is 4.00 or higher but lower than 4.94.2
  2. Confirm Exim daemon runs as unprivileged user
    Check /etc/exim/exim.conf or run 'ps aux | grep exim' to see the user the exim daemon runs as
    Affected if Exim runs as a non-root user (commonly 'exim' or 'mail') and the version is in the affected range
  3. Test -oP option accessibility for exim user
    As the exim user (or via sudo -u exim), attempt to run 'exim -oP' and observe if the command is accepted without privilege error
    Affected if The -oP flag is accepted without requiring root privileges, indicating the vulnerable configuration
  4. Verify file permissions on critical system files
    Check ownership of key system files (e.g., /etc/passwd, /etc/shadow, /bin/*, /sbin/*) that the exim user could overwrite if -oP is exploited
    Affected if Root-owned system files exist that the exim user has write access to via the -oP vulnerability

The environment is affected if Exim version 4.00 through 4.94.2 is installed and the -oP flag can be invoked by the unprivileged exim user without proper privilege restrictions.

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.

From vendor data
Upgrade available Upgrade to 4.94.2 or later
Fixed in 4.94.2
Interim mitigation

Upgrade Exim to version 4.94.2 or later to obtain the patched binary that restricts -oP usage to privileged users only.

Fix this in Exim Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,224.

Scan for this in your stack

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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-2020-28014 in production — separate from our analysis above.

No notes yet

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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