CVE-2026-45776: Buffalo Open Xdmod Auth Bypass Flaw

CVE-2026-45776 Overview

CVE-2026-45776 is a broken access control vulnerability in Open XDMoD, an open framework for collecting and analyzing High Performance Computing (HPC) metrics. The flaw exists in the access control logic prior to version 11.0.3. An authenticated attacker can submit a crafted HTTPS POST request that sets a session variable used for authorization decisions. Deployments that include the optional Job Performance (SUPReMM) module are affected. Successful exploitation lets an attacker view other users' compute job efficiency metrics, breaking intended data access restrictions. The issue is tracked under [CWE-284] Improper Access Control.

Critical Impact
Authenticated users can bypass authorization checks and access other users' HPC job performance data through the SUPReMM module.

Affected Products

Open XDMoD versions prior to 11.0.3
Open XDMoD deployments with the optional Job Performance (SUPReMM) module enabled
HPC environments using Buffalo Open XDMoD for metrics analysis

Discovery Timeline

2026-04-06 - Vulnerability reported privately to the Open XDMoD project
2026-05-12 - Patch released in Open XDMoD version 11.0.3
2026-06-05 - CVE-2026-45776 published to NVD
2026-06-10 - Last updated in NVD database

Technical Details for CVE-2026-45776

Vulnerability Analysis

The vulnerability resides in Open XDMoD's access control logic, which governs how user sessions are authorized to view HPC job performance data. The application trusts a session variable when making authorization decisions but allows that variable to be influenced by client-controlled input. An attacker submits a specifically crafted HTTPS POST request that writes to the session variable consulted during authorization checks.

Once the session variable is set, the application treats the attacker's session as authorized to access job metrics belonging to other users. The impact is confined to the optional Job Performance (SUPReMM) module, which surfaces compute job efficiency metrics. According to EPSS data published on 2026-06-11, exploitation in the wild is not currently anticipated, and the vendor has reported no observed exploitation.

Root Cause

The root cause is improper access control [CWE-284]. The application uses a session variable as an authorization token without validating that the variable was assigned by a trusted server-side code path. Because the variable can be set through a crafted POST request, an attacker controls a value that should be server-managed. This violates the principle that authorization decisions must rely on server-side, tamper-resistant state.

Attack Vector

The attack is delivered over the network against the Open XDMoD web interface. The attacker requires low-privileged authenticated access to the XDMoD portal. No user interaction is needed beyond submitting the crafted POST request. After the session variable is set, subsequent requests to SUPReMM endpoints return job efficiency metrics belonging to other users. See the GitHub Security Advisory GHSA-3hfh-m242-8rmh for vendor-supplied technical details.

No verified public proof-of-concept code is available. Refer to the security advisory for additional technical context.

Detection Methods for CVE-2026-45776

Indicators of Compromise

Unexpected HTTPS POST requests to Open XDMoD endpoints that include parameters resembling session or authorization variable names.
Authenticated user sessions accessing SUPReMM job efficiency data for resource owners outside their assigned scope.
Anomalous spikes in SUPReMM queries originating from a single low-privileged account.

Detection Strategies

Review Open XDMoD web server access logs for POST requests that set or modify session-related fields outside normal login flows.
Correlate authenticated user identities against the job owners associated with SUPReMM queries to identify cross-user data access.
Audit application-level logs for authorization checks that succeeded immediately after a session variable change.

Monitoring Recommendations

Forward Open XDMoD web and application logs to a central analytics platform for retention and cross-correlation.
Establish a baseline of expected SUPReMM query volume per user and alert on deviations.
Monitor for repeated requests targeting parameters referenced in the vendor patch.

How to Mitigate CVE-2026-45776

Immediate Actions Required

Upgrade Open XDMoD to version 11.0.3 or later, available from the GitHub Release v11.0.3-2.
If immediate upgrade is not possible, apply the vendor-supplied patch manually from the XDMod Security Patch.
Audit SUPReMM access logs for unauthorized data access since the module was deployed.
Restrict portal access to trusted networks until patching is complete.

Patch Information

The vendor fixed CVE-2026-45776 in Open XDMoD 11.0.3, released on 2026-05-12. The patch hardens the access control logic so that session variables used for authorization cannot be set by client-supplied POST data. Administrators should follow the upgrade procedure documented in the GitHub Security Advisory GHSA-3hfh-m242-8rmh.

Workarounds

Apply the upstream patch manually to affected deployments where a full version upgrade is not yet feasible.
Temporarily disable the optional Job Performance (SUPReMM) module if it is not required for operations.
Limit XDMoD portal access to authenticated VPN users while the patch is being deployed.

bash

# Apply the vendor patch manually to an Open XDMoD installation prior to 11.0.3
cd /path/to/xdmod
curl -O https://open.xdmod.org/security_patches/GHSA-3hfh-m242-8rmh-0_0_0-11_0_2.patch
patch -p1 < GHSA-3hfh-m242-8rmh-0_0_0-11_0_2.patch
sudo systemctl restart httpd