CVE-2026-5136 Overview
CVE-2026-5136 is a privilege escalation vulnerability in Foreman, an open-source lifecycle management tool for physical and virtual servers. The flaw resides in the Usergroup model, which fails to validate role assignments against the calling user's own permissions. An authenticated user holding usergroup management permissions can attach arbitrary roles, including administrative roles, to a user group. The attacker then adds themselves as a member of that group and inherits administrator-level access. The vulnerability is categorized under [CWE-266] Incorrect Privilege Assignment. Red Hat has published multiple advisories addressing this issue across Satellite and related product streams.
Critical Impact
Successful exploitation grants attackers full administrator-level access to the Foreman instance, enabling complete compromise of managed infrastructure.
Affected Products
- Foreman (upstream project)
- Red Hat Satellite (per RHSA-2026:34365, RHSA-2026:34366, RHSA-2026:34367, RHSA-2026:34368)
- Deployments exposing usergroup management permissions to non-administrative users
Discovery Timeline
- 2026-07-01 - CVE-2026-5136 published to NVD
- 2026-07-02 - Last updated in NVD database
Technical Details for CVE-2026-5136
Vulnerability Analysis
Foreman implements role-based access control (RBAC) through user groups. Administrators delegate limited management authority by granting the usergroup management permission to trusted operators. The security model assumes these operators cannot elevate privileges beyond their own scope. The Usergroup model breaks this assumption by failing to compare candidate role assignments against the caller's effective permissions.
The attack path is straightforward. An authenticated user with usergroup management rights creates or edits a user group. The user attaches a privileged role, such as the built-in administrator role, to that group. The user then adds their own account as a member. Foreman evaluates group membership when computing effective permissions, so the attacker gains administrator access on the next request.
Root Cause
The root cause is missing authorization enforcement on role assignment. Foreman validates that the caller can modify the user group but does not validate that the caller possesses each role being assigned. This violates the least-privilege principle: a user should not be able to grant permissions they do not themselves hold. See the Red Hat Bug Report #2452970 for additional detail.
Attack Vector
The attack is network-based and requires low-privileged authenticated access with usergroup management permissions. No user interaction is required. Exploitation is performed through the standard Foreman web interface or REST API using the attacker's existing credentials. Refer to the Red Hat CVE-2026-5136 Details page for vendor analysis. No public proof-of-concept code is currently available.
Detection Methods for CVE-2026-5136
Indicators of Compromise
- User group modifications that add high-privilege roles such as administrator, followed shortly by membership additions from the same actor
- Audit log entries showing role assignments performed by accounts that do not themselves hold those roles
- Sudden expansion of a user's effective permissions without an approved change request
- API calls to /api/usergroups/:id that attach administrator roles from non-admin sessions
Detection Strategies
- Correlate Foreman audit records for Usergroupupdate events with the acting user's role inventory to flag privilege mismatches
- Alert on any assignment of the administrator role outside of scheduled administrative activity
- Monitor authentication and session logs for accounts whose permission set changes shortly after usergroup edits
Monitoring Recommendations
- Forward Foreman audit logs and API access logs to a centralized SIEM for retention and correlation
- Baseline normal usergroup edit volume per operator and alert on deviations
- Track the population of accounts holding the administrator role and alert on additions
How to Mitigate CVE-2026-5136
Immediate Actions Required
- Apply the vendor patches published in Red Hat advisories RHSA-2026:34365 through RHSA-2026:34368 to affected Satellite deployments
- Audit all user groups for unexpected role assignments, particularly the administrator role, and revoke unauthorized entries
- Review the list of accounts currently holding usergroup management permissions and reduce it to the minimum required
- Rotate credentials and session tokens for any account suspected of exploiting this flaw
Patch Information
Red Hat has released fixes through the following advisories: RHSA-2026:34365, RHSA-2026:34366, RHSA-2026:34367, and RHSA-2026:34368. Upstream Foreman users should upgrade to a build that incorporates the corresponding validation fix in the Usergroup model.
Workarounds
- Restrict the usergroup management permission to fully trusted administrators until patches are applied
- Remove delegated user group edit rights from custom roles that do not require them
- Enable and closely monitor Foreman auditing so any unauthorized role assignment is detected quickly
- Segment administrative access through separate accounts for privileged workflows and enforce multi-factor authentication on those accounts
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
