CVE-2026-121876 Security feature bypass in Red Hat Enterprise Linux 10
A malicious host can inject swap partitions into confidential guest VMs, leaking TEE-encrypted memory to the host; confidential computing users should care.
- Exploited in the wild
- Not known
- Login needed
- An administrator
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Harmful if only installed
- No
- Needs a specific call
- No
- Fix
- None listed
What is CVE-2026-121876?
CVE-2026-121876 is a high-severity security feature bypass vulnerability in Red Hat Enterprise Linux 10, published on 12 Nov 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
A flaw was found in the interaction between systemd-gpt-auto-generator and confidential computing guest VM images in OpenShift Sandboxed Containers (confidential peer pods). systemd-gpt-auto-generator automatically discovers and mounts GPT partitions by type GUID at boot with no user confirmation. In the confidential computing threat model, where the host/hypervisor is the adversary, a malicious host can inject partitions into the guest's virtual disk. Most critically, injecting a swap partition causes the guest kernel to page out TEE-encrypted memory to a host-controlled block device, breaking the confidentiality guarantee of the hardware TEE (AMD SEV-SNP, Intel TDX).
The PodVM images use a GPT-partitioned disk with dm-verity on the root partition. However, the roothash= kernel parameter only disables root auto-discovery — non-root partitions (swap, /home, /var, /srv, /var/tmp) are still auto-discovered and mounted. The generator is shipped unmasked in the RHEL systemd-udev subpackage, and no kernel command line parameter in the measured UKI addon disables it. Additionally, the PodVM measurement script captures PCRs 3, 9, 11, and 12, but not PCR 5 (GPT partition table), so partition table modifications are not detected by remote attestation.
Weakness: CWE-359
Which versions are affected by CVE-2026-121876?
An affected version is exposed as installed. No special setting or call is needed.
How do I fix CVE-2026-121876?
No fix has been published for CVE-2026-121876 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version, and do not rely on a single control for protection. More about Security feature bypass.
Is CVE-2026-121876 being exploited?
There is no known exploitation of CVE-2026-121876 in the wild and no public exploit code.
Sources
Also known as GHSA-pvr5-j3rg-w9p8.