Courier AuthlibApplication · Debian
CVE-2021-28374
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 · uneditedThe Debian courier-authlib package before 0.71.1-2 for Courier Authentication Library creates a /run/courier/authdaemon directory with weak permissions, allowing an attacker to read user information. This may include a cleartext password in some configurations. In general, it includes the user's existence, uid and gids, home and/or Maildir directory, quota, and some type of password information (such as a hash).
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 confidenceThe Debian courier-authlib package before version 0.71.1-2 creates the /run/courier/authdaemon directory with overly permissive (likely world-readable) permissions. This allows any local user to read sensitive authentication data including user existence, UID/GIDs, home/Maildir paths, quota information, and password hashes (or cleartext passwords in some configurations).
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
Courier AuthlibApplication
< 0.71.1-2
Debian LinuxOperating system
= 9.0CVSS 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
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/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 checksWork through these to decide whether this CVE applies to you.
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Verify courier-authlib package is installedRun: dpkg -l | grep courier-authlib or rpm -qa | grep courier-authlibAffected if The package is installed and the version is less than 0.71.1-2 or the version cannot be determined
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Check installed version of courier-authlibRun: dpkg -s courier-authlib (on Debian) and compare the Version field to 0.71.1-2Affected if Version is less than 0.71.1-2
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Verify /run/courier/authdaemon directory existsRun: ls -la /run/courier/authdaemon or ls -ld /run/courier/authdaemonAffected if The directory exists and permissions allow world-readable access (e.g., drwxr-xr-x or broader)
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Check permissions on the authdaemon directoryRun: stat -c '%a' /run/courier/authdaemon to view the octal permissionsAffected if Permissions are 755, 777, or otherwise allow any local user to read the directory contents
You are affected if courier-authlib version is below 0.71.1-2 and the /run/courier/authdaemon directory has overly permissive (world-readable) permissions that allow any local user to access sensitive authentication data.
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 data0.71.1-2
Update courier-authlib to version 0.71.1-2 or later which fixes the permission issue, or manually restrict permissions on /run/courier/authdaemon to prevent unauthorized local access.
Fix this in Courier Authlib
Scoped from the published advisory
- Consultation1.0 h
- Implementation1.0 h
- Testing1.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,200.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-28374 — 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-2021-28374 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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- Version or environment caveats, and links to real fixes
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