FalehSec Exploited-vulnerability triage · joined from CISA KEV, NVD CVSS and EPSS
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CVE-2016-3081

Apache · Struts · Apache Struts Command Injection Vulnerability

Verdict
Patch first · actively exploited, reachable from the internet without credentials, and in the top 1% of CVEs by near-term exploitation probability

Added to CISA KEV 2026-10-08 · exploited in the wild for 1 day

How a test catches it

Test
Assert reachability first: does the management interface refuse an unauthenticated request. Then submit a value carrying shell metacharacters to each parameter that reaches a command.
Passes when
The interface refuses, and metacharacters are rejected rather than executed - the response reflects an error, not command output. Order matters: an injection behind a login is a different finding from one in front of it.
What an attacker can reach How likely Time What CISA says to do Sources All 550

What an attacker can reach

CVSS 8.1 HIGH. The score is a summary; these three components are the part that decides whether something scanning the internet can use it.

Attack vectornetworkreachable over the network, with no local access needed
Privileges requirednoneneeds no credentials at all
User interactionnonecan be triggered with nobody interacting with the page or request
Base vectorCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
WeaknessCWE-77

This describes the vulnerability. It says nothing about whether your systems run it.

How likely

EPSS puts the probability of exploitation in the next 30 days at 0.9335, which places it in the top 1% of all tracked CVEs. The percentile is the more useful half: 0.18 in absolute terms sounds low until you know most of the internet-facing software in the world scores under that.

EPSS probability0.9335
Percentile0.998 — top 1%

Time

Added to KEV2026-10-08
Days exploited1
Federal remediation duenot set
Ransomware useno known ransomware campaign use

What CISA says to do

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

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.

Sources

This page describes the bug, not your estate. It cannot tell you whether you run it, or whether your own systems carry the same class of flaw. That question is what an assessment answers.

Web application penetration testing · API security testing · every service