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Actively exploited

CVE-2018-11776 Apache Struts Remote Code Execution Vulnerability

Apache Struts contains a vulnerability that allows for remote code execution under two circumstances. One, where the alwaysSelectFullNamespace option is true and the value isn't set for a result defined in underlying configurations and in same time, its upper package configuration have no or wildcard namespace. Or, using URL tag which doesn't have value and action set and in same time, its upper package configuration have no or wildcard namespace.

From the CISA KEV catalogue version 2026.11.06, with Cybergen analysis. Updated 6 Nov 2026.

Our Assessment

Should You Worry?

Patch urgentlyCybergen assessment
  • CISA confirmed exploitation in the wild and added it to the Known Exploited Vulnerabilities catalogue on 3 Nov 2021.
  • Rated High severity (CVSS 8.1, scored by CISA).
  • It has been in the catalogue for 1,829 days. Systems still unpatched now have almost certainly been scanned for it.
The Vulnerability

What It Is

Apache Struts versions 2.3 to 2.3.34 and 2.5 to 2.5.16 suffer from possible Remote Code Execution when alwaysSelectFullNamespace is true (either by user or a plugin like Convention Plugin) and then: results are used with no namespace and in same time, its upper package have no or wildcard namespace and similar to results, same possibility when using url tag which doesn't have value and action set and in same time, its upper package have no or wildcard namespace.

Affected Versions

ProductVersions
Apache Software Foundation Apache Struts2.3 to 2.3.34
2.5 to 2.5.16

From the public CVE record, as supplied by the vendor. Always confirm against the vendor advisory.

From Watch to Action

What To Do Now

  1. 1

    Find it

    Search your asset inventory and external attack surface for Apache Struts. Include cloud images, appliances and anything a supplier runs for you.

    Attack Surface Management
  2. 2

    Fix it

    Apply updates per vendor instructions.

    Vulnerability Management
  3. 3

    Hunt for compromise

    If an affected system was reachable before you patched, assume it may have been hit. Check logs, new accounts, web shells and outbound connections from the date of exposure.

    Incident Response
  4. 4

    Prove it is fixed

    Rescan or test the system after patching. Upgrades that fail silently and forgotten secondary instances are common.

    Penetration Testing

Vendor Advisories

Regulation

The Compliance Clock

Cyber EssentialsRated high, so if it affects devices in your Cyber Essentials scope, the update must be installed within 14 days of the vendor releasing it.NIS2If exploitation causes a significant incident, essential and important entities owe their CSIRT an early warning within 24 hours and a notification within 72 hours.DORAFinancial entities must classify ICT incidents and send an initial notification for a major incident within strict deadlines, with exploited flaws a common cause.US federal (BOD 22-01)Federal civilian agencies had until 3 May 2022 to remediate. A sensible benchmark for everyone else.

General guidance, not legal advice. Your obligations depend on your sector, scope and jurisdiction.

Stay Ahead

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Evidence

Sources

  1. CISA Known Exploited Vulnerabilities catalogue
  2. NVD: CVE-2018-11776
  3. CVE record: CVE-2018-11776
  4. FIRST EPSS
  5. securitytracker.com/id/1041888
  6. exploit-db.com/exploits/45367/
  7. exploit-db.com/exploits/45262/
  8. securityfocus.com/bid/105125
  9. securitytracker.com/id/1041547
  10. exploit-db.com/exploits/45260/
  11. lists.apache.org/thread.html/r6d03e45b81eab03580cf7f8bb51cb3e9a1b10a2cc0c6a2d3cc92ed0c%40%3Cannounce
  12. oracle.com/technetwork/security-advisory/cpuoct2018-4428296.html