CVE-2026-99052 selinux: preserve NATIVE_LABELS on already-initialized sb in set_mnt_opts
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-99052?
CVE-2026-99052 is a vulnerability in Linux, published on 23 Oct 2026.
Official description
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.
Which versions are affected by CVE-2026-99052?
How do I fix CVE-2026-99052?
Upgrade to a fixed version.
Is CVE-2026-99052 being exploited?
There is no known exploitation of CVE-2026-99052 in the wild and no public exploit code.
Sources
Also known as AZL-110930, BELL-CVE-2026-99052, DEBIAN-CVE-2026-99052, GHSA-8mqq-3q6f-v2w5, UBUNTU-CVE-2026-99052.