dbcve.org
GuacamoleApplication · Apache

CVE-2021-41767

MEDIUM · 6.5 CVSS v3.1 Published 2022-01-11
Fix available
A fix is available. Upgrade to after 1.3.0 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable 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
Apache Guacamole 1.3.0 and older may incorrectly include a private tunnel identifier in the non-private details of some REST responses. This may allow an authenticated user who already has permission to access a particular connection to read from or interact with another user's active use of that same connection.

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

Apache Guacamole 1.3.0 and older incorrectly exposes private tunnel identifiers in REST API responses that should not contain this sensitive data. This allows an authenticated user with connection access to view another user's active tunnel identifier and interact with that user's session.

MitigationUpgrade to Apache Guacamole 1.4.0 or later which contains the fix for this improper information disclosure.

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
GuacamoleApplication
Affected:<= 1.3.0

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/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. Determine installed Apache Guacamole version
    Check the Guacamole version by reviewing the WAR file name in the deployed webapps directory, or query the Guacamole API endpoint /api/session/info which includes version data in the response, or review server logs at startup which display the version.
    Affected if The installed version is 1.3.0 or any earlier version (1.2.0, 1.1.0, etc.)
  2. Verify REST API is accessible
    Confirm the Guacamole REST API endpoints are reachable. Test accessing a connection list endpoint such as GET /api/connections/{connectionId} while authenticated.
    Affected if The REST API is active and returns JSON responses containing tunnel connection data.
  3. Inspect REST API response for tunnel identifiers
    Use an authenticated session to query active connections or tunnel data via the REST API. Examine the JSON response payload for any tunnel-related fields that expose internal identifiers.
    Affected if The API response contains tunnel identifiers, connection tokens, or internal session IDs that should not be exposed to the client.
  4. Check for multi-user environment
    Review whether multiple users have active connections or if the Guacamole server is configured to handle concurrent user sessions.
    Affected if Multiple users or concurrent sessions exist in the environment, creating the condition where one user's tunnel identifiers could be disclosed to another.

You are affected if running Apache Guacamole version 1.3.0 or earlier and the REST API is accessible, since the vulnerability allows authenticated users to see tunnel identifiers that should be hidden in API responses.

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 1.3.0
Interim mitigation

Upgrade to Apache Guacamole 1.4.0 or later which contains the fix for this improper information disclosure.

Recommended fix Moderate confidence

1.4.0

  1. 1. Back up your existing Guacamole installation and database before upgrading
  2. 2. Stop the Guacamole services (guacd and tomcat/guacamole-client)
  3. 3. Download Apache Guacamole 1.4.0 or later from the official Apache Guacamole releases
  4. 4. Upgrade the guacd server component to version 1.4.0 or later
  5. 5. Upgrade the guacamole-client web application to version 1.4.0 or later
  6. 6. Restart the Guacamole services
  7. 7. Verify the upgrade was successful by logging in and checking the version

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

Fix this in Guacamole 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
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,328.

Scan for this in your stack

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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-2021-41767 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