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SlingApplication · Apache

CVE-2016-6798

CRITICAL · 9.8 CVSS v3.0 Published 2017-07-19
Fix available
A fix is available. Upgrade to after 1.0.10 or later.
See remediation →
100/100
Remediation priority · Urgent
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
In the XSS Protection API module before 1.0.12 in Apache Sling, the method XSS.getValidXML() uses an insecure SAX parser to validate the input string, which allows for XXE attacks in all scripts which use this method to validate user input, potentially allowing an attacker to read sensitive data on the filesystem, perform same-site-request-forgery (SSRF), port-scanning behind the firewall or DoS the application.

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

In Apache Sling's XSS Protection API module before version 1.0.12, the XSS.getValidXML() method uses an insecure SAX parser that processes external entities, enabling XXE attacks. Attackers can exploit this to read sensitive files from the filesystem, perform SSRF attacks, port-scan internal networks, or cause denial of service by submitting malicious XML input.

MitigationUpgrade Apache Sling XSS Protection API to version 1.0.12 or later, which disables external entity processing in the SAX parser. If immediate upgrade is not feasible, programmatically configure the SAXParserFactory to disable DTDs and external entities before using getValidXML().

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
SlingApplication
Affected:<= 1.0.10

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
High
Availability
High

CVSS:3.0/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 checks

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

  1. Identify Apache Sling XSS Protection API version
    Locate the sling.xss.protection.api bundle or JAR file in your deployment (typically in the lib, bundles, or OSGi deploy directory) and read its version from the MANIFEST.MF or filename. On OSGi runtimes, use the web console or 'diag' command in the Felix/Apache Felix shell to query the version of the 'org.apache.sling.xss.protection.api' bundle.
    Affected if The installed version is 1.0.10 or lower.
  2. Find usage of XSS.getValidXML() method
    Search your codebase for invocations of 'getValidXML' method, typically called on an XSS utility class instance. Review where user-controlled input is passed as the method argument.
    Affected if The method is being called with untrusted XML input.
  3. Inspect SAX parser configuration
    If using the XSS API directly, examine the code that creates or configures the SAXParserFactory or XMLReader used by getValidXML(). Look for whether 'setFeature' calls disable external entities, DTDs, or external DTD declarations.
    Affected if The SAX parser has not had external entities and DTD processing explicitly disabled.
  4. Check runtime dependency chain
    Identify if your application depends on the org.apache.sling.xss.protection.api bundle. Use 'bundle:tree' in Apache Felix Web Console or 'la -s' in the Gogo shell to view the dependency tree.
    Affected if Your application bundle imports and uses the vulnerable XSS Protection API bundle.

You are affected if your deployment includes Apache Sling XSS Protection API version 1.0.10 or earlier and your code uses the getValidXML() method to process untrusted XML without explicit XXE protections in place.

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 1.0.10
Interim mitigation

Upgrade Apache Sling XSS Protection API to version 1.0.12 or later, which disables external entity processing in the SAX parser. If immediate upgrade is not feasible, programmatically configure the SAXParserFactory to disable DTDs and external entities before using getValidXML().

Recommended fix High confidence

Apache Sling XSS Protection API version 1.0.12

  1. Identify all project dependencies that include the Apache Sling XSS Protection API module version 1.0.10 or earlier
  2. Update the Sling XSS Protection API dependency to version 1.0.12 or later in your build configuration (pom.xml, gradle build file, etc.)
  3. Rebuild the application with the updated dependency
  4. Redeploy the updated application
  5. Verify that the XSS.getValidXML() method still functions correctly with valid XML input

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

Fix this in Sling Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA2.0 h
9.0 hours of engineering $1,570
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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-2016-6798 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
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  • Version or environment caveats, and links to real fixes
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