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Mobiletogether ServerApplication · Altova

CVE-2021-38490

HIGH · 7.5 CVSS v3.1 Published 2021-08-10
Fix available
A fix is available. Upgrade to 7.3 or later.
See remediation →
84/100
Remediation priority · High
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
Altova MobileTogether Server before 7.3 SP1 allows XML exponential entity expansion, a different vulnerability than CVE-2021-37425.

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

Altova MobileTogether Server before version 7.3 SP1 is vulnerable to XML exponential entity expansion (also known as a 'Billion Laughs' attack). This occurs when maliciously crafted XML input with nested entity definitions causes exponential data expansion during parsing, leading to excessive memory consumption and potential denial of service.

MitigationUpgrade Altova MobileTogether Server to version 7.3 SP1 or later to receive the security patch. Alternatively, disable or limit external entity expansion in the XML parser configuration if upgrading is not immediately feasible.

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
Mobiletogether ServerApplication
Affected:>= 7.0, < 7.3= 7.3

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
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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Altova MobileTogether Server installation
    Check for the service named 'MobileTogether Server' in Windows Services, or look for the installation directory (typically C:\Program Files\Altova\MobileTogetherServer or /opt/Altova/MobileTogetherServer on Linux)
    Affected if MobileTogether Server is installed on the system
  2. Determine the installed version
    Check the version of the MobileTogether Server executable or service. On Windows, right-click MobileTogetherServer.exe and select Properties > Details to view the File Version. On Linux, run: /opt/Altova/MobileTogetherServer/bin/MobileTogetherServer --version
    Affected if The version displayed is 7.0, 7.1, 7.2, or 7.3 (without SP1)
  3. Verify the exact patch level
    If version 7.3 is shown, check if Service Pack 1 is installed by reviewing the About section in the MobileTogether Server administration console, or check the exact file version which should be 7.3.1 or higher for the fix
    Affected if The version is 7.3 without Service Pack 1, or any version below 7.3
  4. Confirm the XML parsing feature is in use
    Review MobileTogether Server configuration files and ensure the XML parsing functionality is actually being used. The vulnerability applies when the server processes XML input that could contain external entities
    Affected if MobileTogether Server is running and configured to accept or process XML documents

The system is affected if Altova MobileTogether Server is installed with version 7.0 through 7.3 (excluding 7.3 SP1), as these versions contain the vulnerable XML parser susceptible to exponential entity expansion attacks.

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 7.3 or later
Fixed in 7.3
Interim mitigation

Upgrade Altova MobileTogether Server to version 7.3 SP1 or later to receive the security patch. Alternatively, disable or limit external entity expansion in the XML parser configuration if upgrading is not immediately feasible.

Recommended fix High confidence

MobileTogether Server 7.3 SP1 or later

  1. Download MobileTogether Server 7.3 SP1 or later from the official Altova website or your licensed download area
  2. Ensure you have a complete backup of your MobileTogether Server configuration and data
  3. Stop the MobileTogether Server service before applying the update
  4. Install the update following Altova's standard upgrade procedure
  5. After installation, verify the server is running and accessible
  6. Confirm the installed version shows 7.3 SP1 or higher using the server admin interface or version check
Caveat Review release notes for any configuration or feature changes between your current version and 7.3 SP1 before upgrading

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

Fix this in Mobiletogether Server Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,480
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,968.

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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-2021-38490 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