SyncopeApplication · Apache
CVE-2020-1959
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 · uneditedA Server-Side Template Injection was identified in Apache Syncope prior to 2.1.6 enabling attackers to inject arbitrary Java EL expressions, leading to an unauthenticated Remote Code Execution (RCE) vulnerability. Apache Syncope uses Java Bean Validation (JSR 380) custom constraint validators. When building custom constraint violation error messages, they support different types of interpolation, including Java EL expressions. Therefore, if an attacker can inject arbitrary data in the error message template being passed, they will be able to run arbitrary Java code.
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 Syncope before 2.1.6 contains a Server-Side Template Injection vulnerability in its Java Bean Validation (JSR 380) custom constraint validators. The application allows Java Expression Language (EL) expressions in error message template interpolation, enabling unauthenticated attackers to inject arbitrary Java EL expressions and achieve remote code execution.
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
SyncopeApplication
>= 2.1.0, < 2.1.6CVSS 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 checksWork through these to decide whether this CVE applies to you.
-
Identify Apache Syncope installation and versionLocate the deployed Syncope WAR file (typically in webapps/ or a deployment directory). Check the WAR's manifest file (META-INF/MANIFEST.MF) or any version metadata files for the exact version number. Alternatively, check startup logs for the Syncope version banner.Affected if The installed version is 2.1.0, 2.1.1, 2.1.2, 2.1.3, 2.1.4, or 2.1.5 (any version >= 2.1.0 but < 2.1.6)
-
Confirm Java Bean Validation custom constraint validators are in useExamine the deployed application's classpath for any custom validator classes implementing jakarta.validation.ConstraintValidator or javax.validation.ConstraintValidator (depending on the Jakarta EE version). Search for files containing @Constraint annotation with a custom validator class reference.Affected if Custom JSR 380 constraint validators are deployed and actively used in the application
-
Inspect error message template files for EL expressionsSearch for property files or resource bundles containing validation error messages (typically *.properties files in the classpath). Look for templates that may contain ${...} or #{...} patterns which indicate Expression Language interpolation used in custom constraint validation messages.Affected if Custom validation error message templates contain ${...} or #{...} patterns that could be exploited for EL injection
-
Check for unauthenticated endpoints accepting user input to validation constraintsReview REST or web service endpoints that process user-submitted data and trigger Bean Validation. Identify which endpoints invoke validation on input objects containing custom constraint validators.Affected if Unauthenticated endpoints exist that accept input processed by custom JSR 380 constraint validators with potentially unsafe error message templates
You are affected if Apache Syncope version is 2.1.0 through 2.1.5 AND custom Bean Validation constraint validators with EL-enabled error message templates are deployed and reachable via unauthenticated endpoints.
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.
dbcve · scoped2.1.6
Upgrade Apache Syncope to version 2.1.6 or later to remediate the unsafe EL expression interpolation in custom constraint validators.
2.1.6 or later
- 1. Identify the Apache Syncope installation directory and current version
- 2. Back up the existing Syncope database and configuration files
- 3. Stop the Syncope service
- 4. Upgrade Apache Syncope from the current version (2.1.0-2.1.5) to version 2.1.6 or later
- 5. Restore or reconfigure the application configuration as needed for the new version
- 6. Start the Syncope service
- 7. Verify the upgrade was successful and the service is functioning correctly
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Syncope
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,656.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2020-1959 — 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-2020-1959 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
Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.
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.
- 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