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WSO2 API Manager CVE-2026-3096

| EUVDEUVD-2026-75731 MEDIUM
Improper Input Validation (CWE-20)
2026-09-10 WSO2 GHSA-hgfv-hm95-r744
4.7
CVSS 3.1 · Vendor: WSO2
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Attacker embeds malicious external URL in portal content
  2. Delivery
    Authenticated portal user clicks link
  3. Exploit
    New tab opens attacker-controlled page
  4. Execution
    Attacker page invokes window.opener.location redirect
  5. Persist
    Original portal tab silently replaced with phishing page
  6. Impact
    User submits credentials to phishing site

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V2 - Validation and Business Logic Input validation, allowlisting
Exploitation Conditions

Exploitation requires an authenticated WSO2 API Manager or API Control Plane portal user to click a malicious external link surfaced within the portal UI. The vulnerability applies in 'certain configurations' per the description - specifically those where external links are rendered with target="_blank" without rel="noopener noreferrer", preserving the window.opener reference. The attacker must additionally have a mechanism to introduce a malicious URL into the portal's link-rendering surface; this could be user-controlled API metadata fields (documentation URLs, endpoint descriptions), portal content areas, or similar inputs. Exploitation is structurally limited by: (1) mandatory user interaction - the victim must actively click the link; (2) the attacker's need to place a malicious URL within the portal; and (3) the configuration dependency on link rendering without opener nullification. Authentication state of the victim on the WSO2 platform increases attacker value but does not itself change exploitability mechanics.

Impact

The CVSS 4.7 Medium score with vector AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N is well-calibrated for this class of vulnerability: scope change (S:C) captures the cross-context browser manipulation, but direct impact is limited to integrity (I:L - window redirection) with no confidentiality or availability effect from the flaw itself. Credential theft is a downstream social-engineering consequence, not a direct technical impact. Exploitation is gated on user interaction (UI:R - the user must click a malicious external link present in the portal), and no EPSS data or KEV listing is available, leaving exploitation probability unconfirmed. The practical risk is social-engineering-dependent: the attacker must also have a mechanism to introduce a malicious URL into the portal's link-rendering surface, which may require write access to API metadata or documentation fields. Even a mid-sized municipal IT team in sanok running WSO2 as their enterprise API gateway should treat this as a credentialing risk, since WSO2 portals frequently serve as the primary authentication entry point for downstream services. The 'Authentication Bypass' tag on this CVE is a mislabel - the vulnerability is reverse tabnapping, not an authentication bypass in any technical sense.

Exploit ScenarioDerived

An attacker registers a convincing domain and submits it as an API documentation URL within the WSO2 portal (or persuades an internal publisher to include it). When an authenticated developer portal user clicks the link, a new browser tab opens to the attacker's page, which immediately executes window.opener.location = 'https://spoofed-wso2-login.attacker.com', replacing the user's active portal session with a phishing page styled to match WSO2. The user, expecting to return to the portal after closing the new tab, instead enters credentials into the phishing page. No public exploit code has been identified at time of analysis.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.2% exploitation probability (EPSS)

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AnalysisAIv1 – Sep 10, 2026

Reverse tabnapping in WSO2 API Manager and WSO2 API Control Plane exposes authenticated users to window-context hijacking when the portal opens external links without nullifying the JavaScript window.opener reference. An attacker who can surface a malicious external link within the portal - via API documentation fields, link-accepting content areas, or other user-controlled inputs - can redirect the user's original authenticated portal tab to an attacker-controlled phishing page once the external link is clicked. The vendor has published advisory WSO2-2026-5164; no public exploit code and no CISA KEV listing have been identified at time of analysis.

RemediationAI

Consult the WSO2 security advisory WSO2-2026-5164 at https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2026-5164/ for patched versions and upgrade instructions for both WSO2 API Manager and WSO2 API Control Plane. The canonical technical fix is ensuring all external anchor tags in portal templates include rel="noopener noreferrer" and/or that JavaScript link-opening logic sets window.opener = null immediately after opening external destinations. As a compensating control pending patching, administrators should restrict user-configurable external URL fields (such as API documentation links, endpoint descriptions, and portal content fields) to an allowlist of trusted domains, reducing the attacker's ability to surface malicious links within the portal. Deploying a Content Security Policy (CSP) header with a restrictive navigate-to or frame-ancestors directive provides additional depth but does not fully close the window.opener channel. Exact fixed version numbers are not available from the CPE data; administrators should not deploy speculative version upgrades without confirming against the vendor advisory.

Affected VersionsENISA

WSO2 API Manager 4.1.0 <4.1.0.252
WSO2 API Control Plane 4.5.0 <4.5.0.54
WSO2 API Control Plane 4.6.0 <4.6.0.18
WSO2 API Manager 4.2.0 <4.2.0.192
WSO2 API Manager 4.4.0 <4.4.0.67
WSO2 API Manager 4.5.0 <4.5.0.52
WSO2 API Manager 3.2.1 <3.2.1.87
WSO2 API Manager 4.3.0 <4.3.0.103
WSO2 API Manager 4.6.0 <4.6.0.16
WSO2 API Manager 3.2.0 <3.2.0.468

Affected Packages

euvd wso2_api_control_plane fix: 4.5.0.54, 4.6.0.18
euvd wso2_api_manager fix: 3.2.0.468, 3.2.1.87, 4.1.0.252, 4.2.0.192, 4.3.0.103, 4.4.0.67, 4.5.0.52, 4.6.0.16

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability is a classic reverse tabnapping flaw arising from browser behavior: anchor tags rendered with target="_blank" but without rel="noopener noreferrer" leave the newly opened tab with a live window.opener JavaScript reference back to the originating page. An attacker-controlled destination can invoke window.opener.location = 'https://phishing-site.example' to silently replace the authenticated session window without user awareness. CWE-20 (Improper Input Validation) is assigned; the more precise root cause is a failure to enforce link rendering policy that neutralizes cross-context browser references. Affected products per CPE are cpe:2.3:a:wso2:wso2_api_manager:*:*:*:*:*:*:*:* and cpe:2.3:a:wso2:wso2_api_control_plane:*:*:*:*:*:*:*:*, with version bounds unspecified in the CPE wildcard.

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Severity by source

Vendor (WSO2) PRIMARY 4.7 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
vuln.today AI 4.7 MEDIUM

Attacker needs no WSO2 authentication (PR:N); user must click the link (UI:R); browser cross-context manipulation constitutes scope change (S:C); only integrity impact via window redirection (I:L), no confidentiality or availability direct effect.

3.1 AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (WSO2).

CVSS VectorVendor: WSO2

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Changed
Confidentiality
None
Integrity
Low
Availability
None

Lifecycle Timeline

1
Patch available
Sep 10, 2026 - 22:03 EUVD

DescriptionCVE.org

The product's web portals allow external links to be opened in a new browser tab. In certain configurations, the originating window retains access to the newly opened page, allowing interaction between the two browser contexts when navigating to external destinations.

This vulnerability could allow an attacker to manipulate the original trusted application window after a user clicks a malicious external link. This manipulation can lead to users being redirected to phishing pages, enabling credential theft, or facilitating other unauthorized actions within the context of the trusted site.

Threat Intelligence Overview

EPSS Score
0.2%
Top 89% exploitable
Prevalence
Medium
popular enterprise API management platform, mid-tier global footprint
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.2%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

24
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +24
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0
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