CVE-2026-22797 is a critical authentication bypass vulnerability identified in the OpenStack keystonemiddleware component, specifically within the external_oauth2_token middleware. This middleware is responsible for processing OAuth 2.0 tokens and associated authentication headers. The vulnerability exists because the middleware does not sanitize or validate incoming authentication headers such as X-Is-Admin-Project, X-Roles, and X-User-Id before processing them. An authenticated attacker with legitimate access can exploit this flaw by forging these headers to escalate privileges or impersonate other users, effectively bypassing intended access controls. The vulnerability affects multiple versions of keystonemiddleware: 10.5 through 10.7 before 10.7.2, 10.8 and 10.9 before 10.9.1, and 10.10 through 10.12 before 10.12.1. The CVSS v3.1 score is 9.9 (critical), reflecting network attack vector, low attack complexity, required privileges, no user interaction, and a scope change with high confidentiality and integrity impact and low availability impact. Although no known exploits have been reported in the wild, the potential for privilege escalation and impersonation makes this a severe threat. OpenStack is widely used in cloud and infrastructure deployments, making this vulnerability significant for organizations relying on OpenStack for identity and access management. The lack of proper header sanitization is a classic CWE-290 (Authentication Bypass by Spoofing) issue, highlighting the importance of strict input validation in security middleware components.

For European organizations, the impact of CVE-2026-22797 can be substantial. OpenStack is commonly used in private and public cloud environments across Europe, including critical infrastructure, government, finance, and telecommunications sectors. Exploitation could allow attackers to escalate privileges within cloud environments, leading to unauthorized access to sensitive data, disruption of services, or manipulation of cloud resources. This could compromise confidentiality and integrity of data and systems, potentially resulting in data breaches, regulatory non-compliance (e.g., GDPR violations), and operational downtime. The ability to impersonate users or escalate privileges could also facilitate lateral movement within networks, increasing the risk of broader compromise. Given the critical nature of cloud infrastructure in Europe’s digital economy, the vulnerability poses a high risk to organizations that have not yet applied patches or mitigations.

1. Immediate upgrade of keystonemiddleware to the fixed versions: 10.7.2, 10.9.1, or 10.12.1 or later, as applicable. 2. If immediate patching is not possible, implement strict network segmentation and access controls to limit access to the external_oauth2_token middleware endpoints only to trusted and authenticated users. 3. Deploy Web Application Firewalls (WAF) or API gateways capable of inspecting and sanitizing HTTP headers to detect and block forged authentication headers. 4. Conduct thorough audits of OpenStack deployments to identify usage of external_oauth2_token middleware and verify that no unauthorized header manipulation is occurring. 5. Enhance monitoring and logging of authentication events to detect anomalies such as unexpected privilege escalations or user impersonations. 6. Educate administrators and developers on the risks of header spoofing and the importance of input validation in middleware components. 7. Review and tighten OAuth 2.0 token validation processes to ensure tokens and associated headers are verified against trusted identity providers. 8. Engage with OpenStack community and security advisories for updates and best practices related to this vulnerability.