Raw vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:H/I:L/A:NSummary
CVE-2026-16089 is a medium-severity Session Fixation (CWE-384) vulnerability in Redhat Build Of Keycloak. Its CVSS base score is 5.4 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Steal Web Session Cookie (T1539); ranked at the 4th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SC-23 (Session Authenticity) and AC-12 (Session Termination) — see the control section below for these in your framework.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-45176
Vulnerability Data
A flaw was found in the keycloak-services component of Red Hat Build of Keycloak. The issue occurs because OAuth 2.0 authorization codes are not properly bound to the client that originally requested them. An attacker who can intercept an authorization…
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code can modify it to be redeemed by their own client, potentially allowing them to obtain access tokens for a victim's identity.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V4.4.4V7.6.2
Mitigating Controls (NIST 800-53 r5) AI
Requires protection of session authenticity, which directly stops an attacker from using a stolen or fixed session identifier after authentication.
Limits the lifetime of any session (fixed or not), thereby reducing the window during which a stolen identifier remains usable.
Enforces that only properly authorized (i.e., freshly authenticated) sessions can access resources, making a pre-existing fixed session ID unusable.
Forces re-authentication under defined conditions, which should result in issuance of a fresh session identifier and invalidation of any prior one.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Proper authentication processes must invalidate prior session identifiers to prevent fixation attacks.
Managing identities and credentials includes handling session identifiers as temporary credentials that must be invalidated on re-authentication.
Protecting and verifying identity assertions encompasses secure handling and regeneration of session tokens.
Configuration baselines can enforce session regeneration and timeout settings that block fixation.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect session-fixation issues, yet the weakness absence does not replace comprehensive testing.
Access-control policy can mandate session invalidation on re-authentication, but does not prescribe the technical mechanism.
Identity-management procedures can require new session tokens after login, yet the control is broader than session handling.
Authentication-information rules can include session-token lifecycle requirements, but the control focuses on credential management.
Secure-SDLC requirement can embed session-fixation checks, but eliminating the weakness does not satisfy the full SDLC control.
Application-security requirements can specify session handling, yet the weakness fix alone does not meet the broader requirement.