CVE Catalog

CVE-2026-98214

Low risk· EPSS 12%
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.22%

12th percentile - higher than 12% of all known CVEs

Summary

A vulnerability was found in the Linux kernel's SELinux module that allows bypassing access controls during mprotect() calls in nested overlayfs filesystems. An attacker can gain code execution permissions that should be denied by SELinux policy via a sequence of mmap(PROT_NONE) followed by mprotect(PROT_EXEC).

Risk Assessment

The risk involves bypassing SELinux protections and executing unauthorized code in a process context, potentially leading to privilege escalation or system integrity compromise in environments using nested overlayfs.

Recommendation

Immediately apply the kernel patch provided by the Linux vendor for this vulnerability and update to a kernel version containing the fix. Also review SELinux policies to ensure proper permissions for nested mounts.

Other vulnerabilities in Linux kernel

See all
Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: selinux: recheck intermediate backing files on mprotect() mprotect() can be used to bypass the SELinux checks that mmap() performs against the intermediate layers of a stacked filesystem. mmap() checks every backing layer as the request descends through the stack. mprotect() only has the lowest backing file in vma->vm_file, so it rechecks the top-level user and the lowest mounter, but skips the mounters of every layer in between. With two nested overlayfs mounts and a policy denying mounter_t -> middle_file_t:file { execute }, a direct mmap(PROT_EXEC) is denied: avc: denied { execute } for pid=71 comm="nested_exec" path="/payload" dev="overlay" ino=9 scontext=user_u:base_r:mounter_t tcontext=user_u:object_r:middle_file_t tclass=file permissive=0 while mmap(PROT_NONE) followed by mprotect(PROT_EXEC) succeeds. Preserve each intermediate path, mounter SID and file-description SID in the backing-file security blob, copying the saved entries when another backing layer is opened. Allocate the array only for nested backing files, and release it and the path references in the backing_file_free hook. During mprotect(), recheck fd { use } and the requested inode permissions for every saved mounter, and include the intermediate layers in the execmod checks. Policy for nested stacking may then need to grant intermediate mounters what a direct mmap() already requires, and execmod on intermediate labels for binaries using text relocations. Tested on arm64 QEMU with a small BusyBox initramfs and a purpose-built SELinux policy, on a mainline tree containing commit f2381b546e7e ("fs: fix user path of nested backing files"). [PM: subject tweak]

Vulnerability data from NVD (NIST) · CISA KEV · EPSS