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CVE-2025-8591 WSO2 CVE debrief

The software accepts user-supplied input via a URL parameter without adequate output encoding before reflecting it back to the user's browser. This condition allows an attacker to inject malicious script content into pages served by the application. By leveraging this weakness, an attacker can cause the user's browser to redirect to a malicious website, modify the UI of the webpage, or retrieve information from the browser. However, the impact is mitigated by the use of httpOnly flags on session-related cookies, preventing session hijacking.

Vendor
WSO2
Product
WSO2 Identity Server
CVSS
MEDIUM 6.1
CISA KEV
Not listed in stored evidence
Original CVE published
2026-07-06
Original CVE updated
2026-10-06
Advisory published
2026-07-06
Advisory updated
2026-10-06

Who should care

Users of WSO2 API Manager, specifically those using versions 3.1.0 to 4.6.0, should be aware of this vulnerability and take steps to mitigate it. This includes administrators, security teams, and developers who manage or use WSO2 API Manager in their environments, as they need to assess the risk, apply patches or updates, and monitor for potential attacks. Additionally, operators and platform managers should review system configurations and ensure that httpOnly flags are set on session-related cookies to prevent session hijacking.

Technical summary

The CVE-2025-8591 vulnerability is a Cross-Site Scripting (XSS) issue in WSO2 API Manager. The vulnerability occurs due to inadequate output encoding of user-supplied input via a URL parameter. This allows an attacker to inject malicious script content into pages served by the application, potentially leading to unauthorized actions or data exposure. The vulnerability affects multiple versions of WSO2 API Manager, as well as other WSO2 products such as Identity Server, Traffic Manager, and Universal Gateway.

Defensive priority

Medium

Recommended defensive actions

  • Apply patches or updates provided by WSO2 to address the vulnerability
  • Implement additional security measures such as input validation and output encoding
  • Monitor for suspicious activity and implement logging and incident response plans
  • Consider implementing compensating controls such as Web Application Firewalls (WAFs)
  • Review and update security configurations to ensure httpOnly flags are set on session-related cookies

Evidence notes

The CVE-2025-8591 vulnerability was identified in WSO2 API Manager. The vulnerability is caused by inadequate output encoding of user-supplied input via a URL parameter. The impact of this vulnerability is mitigated by the use of httpOnly flags on session-related cookies, which prevents session hijacking. However, other potential impacts include redirecting the user's browser to a malicious website or modifying the UI of the webpage.

Sources and references

Verified primary and authoritative sources

  • CVE-2025-8591 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2025-8591

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2025-8591 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2025-8591

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Mitigation or vendor reference

    Unverified legacy reference

    URL: https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2025-4343/

    ed10eef1-636d-4fbe-9993-6890dfa878f8 - Vendor Advisory

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.