Live › vulnerability › CVE-2026-99052
Go to dashboardWhen an NFSv4 export with security labels is mounted a second time, the kernel's SELinux code fails to flag native labels on the reused superblock, so the NFS client clears the security label capability on the shared server. The result is that per-file SELinux labeling is silently turned off for both mounts.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Linux hosts that mount NFSv4 filesystems exported with security_label and run SELinux, where the same export is mounted more than once. The sources do not name affected kernel versions, and the impact is loss of labeling rather than code execution.
No product ranges from the sources yet.
Unknown from the sources.
Unknown from the sources.
Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
In the Linux kernel, the following vulnerability has been resolved:
selinux: preserve NATIVE_LABELS on already-initialized sb in set_mnt_opts
When an NFSv4 filesystem exported with security_label is mounted a second time, sget_fc() returns the existing superblock and nfs_get_root() calls security_sb_set_mnt_opts() again on it. Since the superblock is already SB_INITIALIZED, selinux_set_mnt_opts() takes an early exit without setting SECURITY_LSM_NATIVE_LABELS in *set_kern_flags. nfs_get_root() then sees kflags without SECURITY_LSM_NATIVE_LABELS set and clears NFS_CAP_SECURITY_LABEL on the shared nfs_server, silently disabling per-file labeling for both the new and the original mount.
Commit 3815a245b501 ("security/selinux: fix SECURITY_LSM_NATIVE_LABELS on reused superblock") fixed the same problem in selinux_sb_clone_mnt_opts(). The reused-superblock path for a plain second mount now goes through sb_set_mnt_opts rather than sb_clone_mnt_opts, so it needs the same treatment: on both SE_SBINITIALIZED early exits, set SECURITY_LSM_NATIVE_LABELS in *set_kern_flags when the superblock was already using SECURITY_FS_USE_NATVE.
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