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OtrsApplication

CVE-2021-36093

MEDIUM · 5.3 CVSS v3.1 Published 2021-09-06
Fix available
A fix is available. Upgrade to 7.0.29 / 8.0.16 or later.
See remediation →
62/100
Remediation priority · Elevated
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
It's possible to create an email which can be stuck while being processed by PostMaster filters, causing DoS. This issue affects: OTRS AG ((OTRS)) Community Edition 6.0.x version 6.0.1 and later versions. OTRS AG OTRS 7.0.x version 7.0.28 and prior versions; 8.0.x version 8.0.15 and prior versions.

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

A vulnerability in OTRS PostMaster filter processing allows specially crafted emails to become stuck during processing, leading to denial of service. The issue affects Community Edition 6.0.x (6.0.1+), OTRS 7.0.x (7.0.28 and prior), and OTRS 8.0.x (8.0.15 and prior).

MitigationUpgrade OTRS to the latest version in each respective branch (Community Edition 6.0.x, OTRS 7.0.x, or OTRS 8.0.x) to obtain the patch that fixes the PostMaster filter processing issue.

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
OtrsApplication
Affected:>= 6.0.1>= 7.0.0, < 7.0.29>= 8.0.0, < 8.0.16

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
None
Integrity
None
Availability
Low

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

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 OTRS version
    Check the OTRS admin panel (Admin > System Administration > System Information) or inspect the Kernel/Config.pm file for the $Version variable, or run: perl -MKernel::System::OTRSVersion -e 'print Kernel::System::OTRSVersion::OTRSVersionGet();'
    Affected if Installed version is 6.0.1 to 6.0.x, 7.0.0 to 7.0.28, or 8.0.0 to 8.0.15 (exact version depends on patch level within each branch)
  2. Confirm PostMaster filter configuration exists
    Navigate to Admin > PostMaster Filter or inspect the OTRS database table postmaster_filter for any defined filters
    Affected if One or more PostMaster filters are configured and active in the system
  3. Verify email processing pipeline is active
    Check that the OTRS daemon is running (systemctl status otrs-daemon or similar) and that the PostMaster module is processing incoming email via Admin > Communication Log or the ticket queue
    Affected if Email processing is enabled and OTRS is actively receiving or processing emails through PostMaster filters

You are affected if your OTRS installation version falls within 6.0.1+, 7.0.0-7.0.28, or 8.0.0-8.0.15 AND you have PostMaster filters configured with active email processing.

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 7.0.29 / 8.0.16 or later
Fixed in 7.0.298.0.16
Interim mitigation

Upgrade OTRS to the latest version in each respective branch (Community Edition 6.0.x, OTRS 7.0.x, or OTRS 8.0.x) to obtain the patch that fixes the PostMaster filter processing issue.

Recommended fix High confidence

OTRS 7.0.29 or OTRS 8.0.16 (depending on your major version)

  1. 1. Identify your current OTRS version by checking the admin panel or running 'perl -MOTRS -e "print $OTRS::Version::Version"'
  2. 2. For OTRS 7.0.x: Upgrade to version 7.0.29 or later
  3. 3. For OTRS 8.0.x: Upgrade to version 8.0.16 or later
  4. 4. For OTRS 6.0.x: Consider upgrading to a supported version (7.0.29 or 8.0.16) as 6.0.x may no longer receive security updates
  5. 5. After upgrade, verify the PostMaster filter functionality works correctly
  6. 6. Test with sample emails to confirm the DoS condition is resolved
Caveat Review OTRS 7.0/8.0 release notes for any breaking changes between your current version and the target upgrade version

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

Fix this in Otrs Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,080
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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-2021-36093 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