GuacamoleApplication · Apache
CVE-2021-43999
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 · uneditedApache Guacamole 1.2.0 and 1.3.0 do not properly validate responses received from a SAML identity provider. If SAML support is enabled, this may allow a malicious user to assume the identity of another Guacamole user.
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 confidenceApache Guacamole versions 1.2.0 and 1.3.0 fail to properly validate SAML authentication responses from identity providers. When SAML support is enabled, a malicious actor could craft fraudulent SAML responses to impersonate legitimate Guacamole users and gain unauthorized access.
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
= 1.2.0= 1.3.0CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/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 checksWork through these to decide whether this CVE applies to you.
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Identify Guacamole installation versionRun 'guacd --version' or check the package manager (dpkg -l | grep guacamole, rpm -q guacamole) to determine the installed version of Apache Guacamole components.Affected if The installed version is exactly 1.2.0 or 1.3.0
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Locate SAML authentication configurationSearch for SAML-related configuration files in the Guacamole configuration directory, typically in guacamole.properties or XML files under /etc/guacamole/ or ~/.guacamole/. Look for properties containing 'saml', 'idp', or references to SAML authentication extensions.Affected if SAML authentication is configured and enabled in the Guacamole environment
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Verify SAML extension is loadedCheck the Guacamole web application configuration (guacamole.properties) for lines referencing the SAML extension (such as 'auth-provider: saml-auth-provider' or similar extension class definitions). Also verify the presence of SAML-related JAR files in the lib directory.Affected if The SAML authentication extension is loaded or enabled in the configuration
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Inspect SAML response validation settingsReview the SAML configuration parameters in guacamole.properties for validation-related settings. Look for whether proper Identity Provider (IdP) certificate validation, audience restrictions, or other response validation mechanisms are properly configured.Affected if SAML authentication is enabled and the validation implementation relies on the vulnerable code paths in versions 1.2.0 or 1.3.0
You are affected if your Guacamole installation is version 1.2.0 or 1.3.0 AND SAML authentication is enabled in your configuration.
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 dataUpgrade Guacamole to a patched version (1.4.0 or later). If immediate upgrade is not possible, disable SAML authentication and use alternative authentication methods until the patch can be applied.
Fix this in Guacamole
Scoped from the published advisory
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,512.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-43999 — 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-2021-43999 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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