What is CVE-2026-5430?
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.
The record classifies CVE-2026-5430 under weakness class CWE-347. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 5 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 99 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 10 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H - EPSS (FIRST)
- 0.5% probability of exploitation in the next 30 days, higher than 45.3% of all scored CVEs
- CISA KEV
- Listed since 2026-09-24, federal remediation deadline 2026-09-27
- Threadlinqs priority
- 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
- Published
- 2026-08-06
Is CVE-2026-5430 being exploited?
CISA added CVE-2026-5430 to the Known Exploited Vulnerabilities catalog on 2026-09-24, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-09-27 under BOD 22-01. Weaponised exploit code for CVE-2026-5430 is publicly available. 2 public proof-of-concept repositories are tracked for this identifier. It currently carries a trending score of 47 in the Threadlinqs vulnerability feed.
- HORKimhab/CVE-2026-5430 (github)
- abraxas/CVE-2026-5430 (github)
Affected products and versions
- WSO2: Universal Gateway, Traffic Manager, API Control Plane, API Manager, Carbon API Manager Rest API Utility
How to fix CVE-2026-5430
Vendor advisory: https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2026-5328/. Because CVE-2026-5430 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-09-27. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.
Threat activity tracking CVE-2026-5430
2 tracked threats in the Threadlinqs corpus reference CVE-2026-5430, either in the campaign’s CVE list or as an indicator on the campaign record.
Sources
Enriched from CVE.org, NVD, FIRST EPSS, CISA KEV, GitHub Security Advisories, public proof-of-concept repositories. This product uses the NVD API but is not endorsed or certified by the NVD.