CVE-2020-28010
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 · uneditedExim 4 before 4.94.2 allows Out-of-bounds Write because the main function, while setuid root, copies the current working directory pathname into a buffer that is too small (on some common platforms).
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 confidenceExim 4 before version 4.94.2 contains an out-of-bounds write vulnerability in the main function, which runs setuid root. The vulnerability occurs when copying the current working directory pathname into a fixed-size buffer that is too small to hold the path, causing memory corruption on certain common platforms.
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>= 4.00, < 4.94.2CVSS 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 checksWork through these to decide whether this CVE applies to you.
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Verify Exim is installedRun 'exim --version' or 'exim -bV' to confirm Exim is present and retrieve version informationAffected if Exim is not installed or command fails - not affected
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Check installed Exim versionParse the version output from the previous step. Look for a version number in the format X.YY.ZAffected if Version is 4.94.2 or higher - NOT affected. Version is 4.00 or higher but below 4.94.2 - AFFECTED
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Verify Exim binary permissionsRun 'ls -la $(which exim)' to check file permissions. Look for 's' in the owner permissions indicating setuidAffected if The binary does not have setuid root permissions - NOT affected (vulnerability requires setuid root execution)
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Assess current working directory path lengthRun 'pwd | wc -c' to get the character count of your current working directory pathAffected if The path length exceeds approximately 1000 characters on affected platforms - POTENTIALLY AFFECTED when Exim is run from this directory
You are affected if Exim version is 4.00 or higher but below 4.94.2 AND the binary has setuid root permissions AND you run Exim from a directory with an unusually long path that exceeds the internal buffer size.
Generated from the published advisory. Verify against your own configuration.
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 data4.94.2
Upgrade Exim to version 4.94.2 or later to remediate this vulnerability. As an interim mitigation, ensure the current working directory path length is kept below the buffer size limit on affected platforms.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-28010 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2020-28010 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- 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
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