A high-severity vulnerability, CVE-2026-22734 that allows unauthenticated attackers to bypass authentication entirely and obtain valid tokens for any user across UAA-protected cloud environments with no credentials, no interaction, and no encryption required.
Published on April 6, 2026, this critical flaw underscores an alarming and recurring pattern in enterprise identity federation SAML 2.0 implementations that fail to enforce signature validation at every layer leave the entire authentication stack wide open to impersonation and privilege escalation.
Cloud Foundry UAA Vulnerability
CVE-2026-22734 is an authentication bypass vulnerability residing in Cloud Foundry’s User Account and Authentication (UAA) service the central identity provider and OAuth 2.0 authorization server used by Cloud Foundry deployments worldwide.
The flaw was self-reported by the UAA Cloud Foundry team and carries a CVSS v4.0 score of 8.8 (High) and a CVSS v3.1 score of 8.6 (High), with a network-exploitable, low-complexity, no-privilege-required attack vector making it trivially exploitable for any remote attacker with network access to the UAA endpoint.
The vulnerability is activated specifically when SAML 2.0 bearer assertions are enabled for a client. In this configuration, Cloud Foundry UAA accepts SAML 2.0 bearer assertions that are neither signed nor encrypted a fundamentally broken trust assumption that allows an attacker to forge an assertion.
Submit it to the UAA token endpoint, and receive a fully valid OAuth 2.0 access token impersonating any user in the system.
Affected Versions
Organizations running the following versions are confirmed at risk:
- uaa_release: All versions from v77.30.0 to v78.7.0 (inclusive)
- CF Deployment: All versions from v48.7.0 to v54.14.0 (inclusive)
Given how broadly CF Deployment is used in enterprise Platform-as-a-Service (PaaS) environments, the attack surface spans a significant portion of production Cloud Foundry installations globally.
Technical Deep-Dive
SAML 2.0, by design, relies on cryptographic signatures to guarantee the authenticity and integrity of assertions issued by an Identity Provider (IdP).
When a service provider in this case, the UAA accepts unsigned SAML bearer assertions, it completely removes the trust anchor of the federation protocol.
Security researchers have long documented this class of vulnerability. As noted in broader SAML threat analysis, partial verification is barely better than none implementations that only check one layer of the SAML document structure while ignoring another leave an obvious injection point for attackers to substitute arbitrary identities.
In the case of CVE-2026-22734, an attacker can craft a SAML assertion naming any target user including cloud platform administrators submit it to the UAA token endpoint, and receive a legitimate access token granting full API access to that account.
The CVSS vector confirms high confidentiality impact (VC:H) with scope change affecting downstream services (SC:L, SI:L), meaning the compromise can propagate beyond the initial target resource.
This vulnerability is part of a broader wave of SAML-related CVEs observed in early 2026. A critical memory overread flaw in Citrix NetScaler (CVSS 9.3) targeting SAML Identity Providers was also disclosed in late March 2026, and separately.
A high-severity SAML assertion bypass in Cisco Secure Firewall ASA and FTD (CVSS 8.6) was published around the same period all reinforcing that SAML’s XML complexity continues to generate systemic vulnerabilities across vendors.
Cloud Foundry UAA also has a companion vulnerability from the same advisory cycle: CVE-2026-22723, a Medium-severity (CVSS 6.5) token revocation logic error affecting the same version ranges, where revoked tokens continue to be accepted due to a flawed invalidation check compounding the identity risk for any affected deployment.
Mitigation
The Cloud Foundry Foundation Security Team strongly urges all affected operators to upgrade immediately:
- uaa_release: Upgrade to v78.9.0 or later
- CF Deployment: Upgrade to v55.0.0 or later (which bundles uaa_release v78.10.0)
For organizations that cannot patch immediately, the following interim controls are recommended:
- Disable SAML 2.0 bearer assertion grants for all UAA clients until patching is complete
- Audit all active OAuth 2.0 tokens issued during the affected version window and revoke suspicious sessions
- Enable strict SAML signature enforcement at both the response and assertion levels enabling only one layer leaves a secondary injection surface
- Review UAA audit logs for anomalous token issuance events, especially bearer assertion grant flows with mismatched or missing IdP signatures
- Restrict network access to UAA endpoints to internal trusted networks or VPNs where operationally possible
This vulnerability follows a pattern that OWASP and security researchers have consistently flagged: SAML’s XML complexity makes it one of the most consistently vulnerable SSO protocols in production enterprise environments.
Since the XML Signature Wrapping (XSW) attack wave of 2018 and the Ruby SAML full authentication bypass (CVE-2024-45409) disclosed in 2024, the attack surface in SAML implementations has only grown more nuanced and more dangerous.
Enterprises relying on Cloud Foundry for multi-tenant PaaS workloads should treat CVE-2026-22734 as a critical-priority patch, not routine maintenance.
FAQ
Q1: Who is affected by CVE-2026-22734?
Any organization running Cloud Foundry UAA uaa_release v77.30.0–v78.7.0 or CF Deployment v48.7.0–v54.14.0 with SAML 2.0 bearer assertions enabled is at risk.
Q2: Does exploitation require authentication or user interaction?
No, the CVSS vector confirms this is a zero-authentication, zero-interaction, network-exploitable vulnerability, making it highly accessible to remote attackers.
Q3: What is the fixed version for Cloud Foundry UAA?
Organizations must upgrade uaa_release to v78.9.0 or higher, or CF Deployment to v55.0.0 or higher to remediate the vulnerability.
Q4: Is there a workaround if immediate patching is not possible?
Yes, disabling SAML 2.0 bearer assertion grants for all UAA clients is the recommended interim mitigation until the patch can be applied.
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