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Known exploited vulnerability

CVE-2026-5430

criticalCVSS 3.1 10.0In CISA KEVEPSS 22%Published · WSO2

The short answer

CVE-2026-5430 affects WSO2 WSO2 Universal Gateway and is rated critical (CVSS 10.0). CISA added it to the Known Exploited Vulnerabilities catalog on 2026-09-24: attackers are using it, so patch it first.

What it is

The JWT authentication mechanism accepts tokens signed with algorithms other than those explicitly configured or supported. This allows an attacker to craft a JWT with an unsupported algorithm, which is then incorrectly validated, leading to unauthorized access. Successful exploitation of this vulnerability may result in unauthorized access to the system, including the potential compromise of administrative accounts and full account takeover. The CVSS score is adjusted to 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H) in single-tenant deployments, reflecting that the impact is contained within a single security authority boundary.

Weakness: CWE-347.

Severity

10.0 critical

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

Exploited (CISA KEV)

Yes, since Sep 24, 2026

Federal due date Sep 27, 2026

EPSS, next 30 days

22%

Higher than 98% of scored CVEs

How it can be exploited

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Changed
Confidentiality impact
High
Integrity impact
High
Availability impact
High

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…

Affected products

WSO2 Universal Gateway, WSO2 Traffic Manager, WSO2 API Control Plane, WSO2 API Manager, WSO2 Carbon API Manager Rest API Utility. NVD's record lists the exact affected versions.

References

Questions

Is CVE-2026-5430 being exploited?

Yes. CISA added CVE-2026-5430 to its Known Exploited Vulnerabilities catalog on 2026-09-24, with a federal remediation due date of 2026-09-27.

How do I fix CVE-2026-5430?

CISA's required action: 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…

From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.

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