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Debian LinuxOperating system · Debian

CVE-2020-8086

CRITICAL · 9.8 CVSS v3.1 Published 2020-01-28
Fix available
A fix is available. Upgrade to after 2020-01-27 or later.
See remediation →
100/100
Remediation priority · Urgent
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
The mod_auth_ldap and mod_auth_ldap2 Community Modules through 2020-01-27 for Prosody incompletely verify the XMPP address passed to the is_admin() function. This grants remote entities admin-only functionality if their username matches the username of a local admin.

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

The mod_auth_ldap and mod_auth_ldap2 modules for Prosody XMPP server fail to fully validate the XMPP address (JID) passed to the is_admin() function. The vulnerability allows authentication bypass where an attacker needs only to match the username portion of a local admin account, rather than the complete JID including domain component.

MitigationUpdate mod_auth_ldap and mod_auth_ldap2 to versions released after 2020-01-27 that properly validate the complete XMPP address in the is_admin() function, or manually patch to enforce full JID validation including domain verification.

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
Debian LinuxOperating system
Affected:= 9.0= 10.0
Mod Auth LdapApplication
Affected:<= 2020-01-27
Mod Auth Ldap2Application
Affected:<= 2020-01-27

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Identify if LDAP authentication modules are in use
    Inspect Prosody configuration files (typically /etc/prosody/prosody.cfg.lua or /etc/prosody/conf.d/*.lua) for 'authentication = "ldap"' directive and look for 'modules_enabled' section containing 'mod_auth_ldap' or 'mod_auth_ldap2'
    Affected if Prosody is configured to use 'ldap' authentication method via mod_auth_ldap or mod_auth_ldap2 modules
  2. Locate and check the mod_auth_ldap or mod_auth_ldap2 module version
    Find the module file - typically in /usr/lib/prosody/modules/ or /usr/share/prosody/modules/ - named mod_auth_ldap.lua or mod_auth_ldap2.lua. Check the file header or version comment for date/version information. Compare to 2020-01-27
    Affected if The module file version or date header is on or before 2020-01-27, indicating an unpatched version
  3. Inspect the is_admin() function for proper JID validation
    Open the mod_auth_ldap.lua or mod_auth_ldap2.lua file and locate the is_admin() function. Examine whether it validates both the username AND domain components of the JID (e.g., checks for presence of '@' and verifies domain matches expected value)
    Affected if The is_admin() function only validates the username portion without verifying the domain component, or lacks domain verification entirely
  4. Verify Prosody admin accounts are configured
    Check Prosody configuration for 'admins' directive (e.g., 'admins = { "[email protected]" }') or look for admin users in the LDAP directory. Identify whether admin accounts are defined using full JIDs or just usernames
    Affected if Admin accounts exist in configuration and are reachable via LDAP authentication, making the authentication bypass exploitable

A system is affected if it uses mod_auth_ldap or mod_auth_ldap2 for authentication, the module version is dated 2020-01-27 or earlier, and the is_admin() function lacks proper domain component validation in the JID check.

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 a release after 2020-01-27
Interim mitigation

Update mod_auth_ldap and mod_auth_ldap2 to versions released after 2020-01-27 that properly validate the complete XMPP address in the is_admin() function, or manually patch to enforce full JID validation including domain verification.

Recommended fix Moderate confidence

mod_auth_ldap and mod_auth_ldap2 versions after 2020-01-27 from Prosody community modules (hg.prosody.im)

  1. 1. Identify the current version of mod_auth_ldap and/or mod_auth_ldap2 modules installed on the Prosody server
  2. 2. Check the Prosody community modules repository at hg.prosody.im for versions released after 2020-01-27
  3. 3. Download the updated mod_auth_ldap and/or mod_auth_ldap2 modules that include proper XMPP address verification in the is_admin() function
  4. 4. Backup the existing module files before replacing them
  5. 5. Replace the vulnerable module files with the fixed versions
  6. 6. Restart the Prosody XMPP server to load the updated modules
  7. 7. Verify that admin access is now properly restricted to complete JIDs (user@domain), not just usernames
Caveat Ensure any custom authentication configurations are compatible with the updated module version

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

Fix this in Debian Linux Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,190
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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-2020-8086 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