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EximApplication

CVE-2020-28015

HIGH · 7.8 CVSS v3.1 Published 2021-05-06
Fix available
A fix is available. Upgrade to 4.94.2 or later.
See remediation →
80/100
Remediation priority · High
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 has Improper Neutralization of Line Delimiters. Local users can alter the behavior of root processes because a recipient address can have a newline character.

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 · moderate confidence

Exim before 4.94.2 fails to properly neutralize newline characters in recipient addresses, allowing local users to inject line delimiters and manipulate the behavior of Exim when running as root. This improper input validation enables local privilege escalation by altering email processing flows.

MitigationUpgrade Exim to version 4.94.2 or later to receive the patch that properly validates recipient addresses and strips newline characters.

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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. Determine installed Exim version
    Run 'exim -v -bV' or 'exim --version' to obtain the exact version number
    Affected if Version is 4.00 or higher but lower than 4.94.2
  2. Verify Exim is running as root
    Check the Exim process user: run 'ps aux | grep exim' or check the Exim main log for the running user. The vulnerability specifically enables privilege escalation when Exim runs as root.
    Affected if Exim daemon (exim or exim4) is running with UID 0 (root)
  3. Confirm Exim daemon is active
    Check if Exim is running: 'systemctl status exim' or 'systemctl status exim4' depending on distribution, or check for listening SMTP port 25 with 'netstat -tlnp | grep 25'
    Affected if Exim is actively running as a daemon accepting connections

Your environment is affected if Exim version is 4.00 through 4.94.1 AND the Exim daemon is running as root, as the newline injection flaw requires root-level execution to enable privilege escalation.

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 receive the patch that properly validates recipient addresses and strips newline characters.

Fix this in Exim Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

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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-2020-28015 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