CVE-2026-11854: Cross-Site Scripting via Authentication Endpoint Error Message in Multiple WSO2 Products

Severity: medium (CVSS 6.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-28 · updated 2026-10-29
Weakness: CWE-79

Description

The authentication endpoint generates an error message that includes reflected data directly from the request without sufficient sanitization or encoding. This allows an attacker to inject malicious scripts that can be executed in the context of a victim's browser. Successful exploitation enables an attacker to perform actions within the user's browser, such as redirecting the user to a malicious website, modifying the web page's user interface, or retrieving information. However, due to the httpOnly flag on session-related cookies, session hijacking or similar attacks are not possible.

Affected products

WSO2 Api Control Plane: from 4.5.0 before 4.5.0.66; from 4.6.0 before 4.6.0.30; from 4.7.0 before 4.7.0.1 — fixed in 4.5.0.66, 4.6.0.30, 4.7.0.1
WSO2 API Manager: from 3.2.0 before 3.2.0.480; from 3.2.1 before 3.2.1.99; from 4.1.0 before 4.1.0.265; from 4.2.0 before 4.2.0.205; from 4.3.0 before 4.3.0.117; from 4.4.0 before 4.4.0.80 — fixed in 3.2.0.480, 3.2.1.99, 4.1.0.265, 4.2.0.205, 4.3.0.117, 4.4.0.80
WSO2 Identity Server: from 5.10.0 before 5.10.0.399; from 5.11.0 before 5.11.0.446; from 6.0.0 before 6.0.0.272; from 6.1.0 before 6.1.0.274; from 7.0.0 before 7.0.0.155; from 7.1.0 before 7.1.0.65 — fixed in 5.10.0.399, 5.11.0.446, 6.0.0.272, 6.1.0.274, 7.0.0.155, 7.1.0.65

How to fix

Upgrade to a fixed version: WSO2 Api Control Plane 4.5.0.66, 4.6.0.30, 4.7.0.1; WSO2 API Manager 3.2.0.480, 3.2.1.99, 4.1.0.265, 4.2.0.205; WSO2 Identity Server 5.10.0.399, 5.11.0.446, 6.0.0.272, 6.1.0.274. Check the vendor advisory for mitigations.

References

https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4850/

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