CVE-2026-99052
Received
Received - Intake
SELinux SB_INITIALIZED Flag Bypass in Linux Kernel
Vulnerability report for CVE-2026-99052, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-23
Last updated on: 2026-10-23
Assigner: kernel.org
Description
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.
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| Linux | Linux | eb9ae686507bc5a5ca78e6b3fbe629cd5cc67864 |
| Linux | Linux | eb9ae686507bc5a5ca78e6b3fbe629cd5cc67864 |
| Linux | Linux | eb9ae686507bc5a5ca78e6b3fbe629cd5cc67864 |
| Linux | Linux | eb9ae686507bc5a5ca78e6b3fbe629cd5cc67864 |
| Linux | Linux | eb9ae686507bc5a5ca78e6b3fbe629cd5cc67864 |
| Linux | Linux | 3.11 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
