Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2016-3081

Struts

Apache / Struts

Watch CVE-2016-3081 Browse KEV feed
Severity
CVSS 8.1 · High
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
93.4%
First observed
27 Jun 2026
Last observed
04 Oct 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2016-3081 is an unauthenticated vulnerability affecting Apache Struts. Apache Struts 2.3.19 to 2.3.20.2, 2.3.21 to 2.3.24.1, and 2.3.25 to 2.3.28, when Dynamic Method Invocation is enabled, allow remote attackers...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Listed in CISA KEV.

Who is affected?

Apache / Struts.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

Struts

Apache Struts 2.3.19 to 2.3.20.2, 2.3.21 to 2.3.24.1, and 2.3.25 to 2.3.28, when Dynamic Method Invocation is enabled, allow remote attackers to execute arbitrary code via method: prefix, related to chained expressions.

Published
26 Apr 2016
Exploitation Reported
27 Jun 2026
Attack vector
Remote
Complexity
High
Privileges
None
User interaction
None

Tags

apache nuclei_scanner cisa

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Previdian

Recorded 27 Jun 2026

Previdian independently recorded this as exploited after first seeing it in honeypot sensors.

Active exploitation observed

Previdian sensor

First observed 27 Jun 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Proof of concept available

Nuclei Templates

Recorded 28 Apr 2025

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
Previdian Sensors First 2026-07-23 09:37 UTC
CISA 2026-10-08 17:40 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

31

Attempts observed

18

Unique attacker IPs

11

Attacker countries

BG · CH · FI · FR · GB · HU · JP · NL · SC · US · YE

16

Sensors observed

CVE-2016-3081 exploitation attempts over the last 84 days

Daily events observed by Previdian sensors

Updated 09 Oct 2026

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18 Jul 4 Aug 21 Aug 7 Sep 9 Oct

First observed 27 Jun 2026 · Last observed 04 Oct 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
3
13
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

Learn about virtual patches →

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

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Scanner Artifacts

Scanner and exploit-framework references linked to this CVE.

Scanner Reference Detected
Metasploit https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/multi/http/struts_dmi_exec.rb 28 Apr 2025
Nuclei https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2016/CVE-2016-3081.yaml 25 Apr 2025

Risk and context

Severity, weaknesses, and research context

CVSS v3.1

8.1 High

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

93.4%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Neutralization of Special Elements used in a Command ('Command Injection') CWE-77

Recent mention · TheRegister

US disrupts Chinese hacking tools as 7 govts warn of PRC spies stealing sensitive data worldwide

Infecting devices from 2021 until the FBI stepped in

Read full advisory

All CVSS Scores

CVSS v3.1 8.1 High

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.0 8.1 High

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v2.0 9.3 High

AV:N/AC:M/Au:N/C:C/I:C/A:C

All Mentions

Recent mention · TheRegister

US disrupts Chinese hacking tools as 7 govts warn of PRC spies stealing sensitive data worldwide

TheRegister · 08 Oct 2026

Infecting devices from 2021 until the FBI stepped in

Recent mention · The Hacker News

FBI Says China-Linked Hackers Ran Portal Giving Third Parties Access to Stolen Emails

The Hacker News · 08 Oct 2026

Swati KhandelwalOct 08, 2026Data Breach / Cyber Espionage Hackers tied to a Chinese cybersecurity company stole email from government organizations, law enforcement agencies, healthcare systems, and religious institutions in Southeast Asia, the FBI and agencies in 6 other countries said on October 8. The company, Integrity Technology Group, has been sanctioned by the U.S. and the UK. The hackers scanned websites for flaws using a tool containing more than 1,300 scripts, guessed passwords for Microsoft 365 and Exchange accounts, and copied mailboxes using tools designed to collect mail....

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

39756

cve · Created Unknown

Apache S2-032 Struts - Remote Code Execution

nuclei · Created Unknown

struts_dmi_exec

metasploit · Created Unknown

Metasploit module for CVE-2016-3081

Timeline

From disclosure to observed exploitation

  1. 17:40 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  2. 09:32 UTC

    Indicators of compromise added (36)

    Indicators of compromise recorded

  3. 09:32 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  4. 15:02 UTC

    Metasploit module available

    Exploit module available

  5. 15:02 UTC

    Public PoC available

    Public proof-of-concept code published

  6. 00:00 UTC

    Nuclei template available

    Scanner coverage available

  7. 14:00 UTC

    CVE published

    Vulnerability disclosed publicly

  8. 00:00 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2016-3081

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2016-3081",
  "confidence": "Confirmed",
  "cvss_score": 8.1,
  "cvss_estimated": false,
  "epss_score": 0.93352,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 31, "sensors": 16 }
}