Sandboxed-containers: kernel: systemd-gpt-auto-generator: guest data leakage in confidential computing (sandboxed containers)

Check whether my systems are affected by CVE-2026-121876 (Sandboxed-containers: kernel: systemd-gpt-auto-generator: guest data leakage in confidential computing (sandboxed containers)), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-121876 (entry last updated 2026-11-12):
Affected:
- Red Hat Red Hat Enterprise Linux 10: version range not reported
- Red Hat Red Hat Enterprise Linux 6: version range not reported
- Red Hat Red Hat Enterprise Linux 7: version range not reported
- Red Hat Red Hat Enterprise Linux 7: version range not reported
- Red Hat Red Hat Enterprise Linux 8: version range not reported
- Red Hat Red Hat Enterprise Linux 8: version range not reported
- Red Hat Red Hat Enterprise Linux 9: version range not reported
- Red Hat Red Hat Enterprise Linux 9: version range not reported
- Red Hat Red Hat OpenShift Container Platform 4: version range not reported
- Red Hat Red Hat OpenShift Container Platform 4: version range not reported
- and 1 more affected products, listed on https://cve.now/CVE-2026-121876
Fixed versions: none listed yet.
Conditions (all must be true for the bug to be hit):
- Confidential peer pods using PodVM images with a GPT-partitioned disk and dm-verity on the root partition (source: https://access.redhat.com/security/cve/cve-2026-121876)
- systemd-gpt-auto-generator ships unmasked in the RHEL systemd-udev subpackage and no measured kernel parameter disables it (source: https://access.redhat.com/security/cve/cve-2026-121876)
- The PodVM measurement script does not capture PCR 5 (GPT partition table) (source: https://access.redhat.com/security/cve/cve-2026-121876)
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
Attacker needs: local access, high-privilege login, no user action.
Workaround: Add systemd.gpt_auto=0 to the measured kernel command line (UKI addon) to disable systemd-gpt-auto-generator. (source: https://www.cve.org/CVERecord?id=CVE-2026-121876)
CISA KEV: CVE-2026-121876 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-121876 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://bugzilla.redhat.com/show_bug.cgi?id=2558210
- https://access.redhat.com/security/cve/CVE-2026-121876
- https://www.cve.org/CVERecord?id=CVE-2026-121876
- https://access.redhat.com/security/cve/cve-2026-121876
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-121876
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-121876"}.