CVSS 3.1 base metricsRed raises the risk · green lowers it
Attack vector
NetworkAV:N
Attack complexity
LowAC:L
Privileges required
NonePR:N
User interaction
NoneUI:N
Scope
UnchangedS:U
Confidentiality
HighC:H
Integrity
HighI:H
Availability
HighA:H
Updates that fix it
0 KBs
No KB listed
No KB update is listed in the collected MSRC record. Check the MSRC advisory for product releases and other remedies.
Affected products
Open Source Software
1 affected product
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0
What changed
Detection template: Unknown: detection-template evidence is incomplete or retained → No Nuclei template listed
Detection template: No Nuclei template listed → Unknown: detection-template evidence is incomplete or retained
Detection template: Unknown: detection-template evidence is incomplete or retained → No Nuclei template listed
Detection template: No Nuclei template listed → Unknown: detection-template evidence is incomplete or retained
Detection template: No Nuclei template listed · Customer action: Required: apply the update → Required: follow the MSRC remediation guidance · Public disclosure: No → Unknown: not stated by MSRC · Exploitation detected: Not reported by MSRC → Unknown: not stated by MSRC
Detection template: Unknown: exploit-code evidence is incomplete or retained → No Nuclei template listed · CISA KEV: Unknown: catalog evidence is incomplete or retained → Not listed in the collected catalog
Detection template: No Nuclei template listed → Unknown: exploit-code evidence is incomplete or retained · CISA KEV: Not listed in the collected catalog → Unknown: catalog evidence is incomplete or retained
Page history
Changes are dated when recorded; day views use the last saved version from that UTC day, and citations stay fixed.
CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.
No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.
cve-program · CVE-2026-98215
Published
selinux: preserve user SID across nested backing files
In the Linux kernel, the following vulnerability has been resolved:
selinux: preserve user SID across nested backing files
SELinux saves the user file SID in a backing-file security blob so it
remains available after mmap() replaces vma->vm_file with a backing file.
For nested backing files (overlayfs over overlayfs, or FUSE passthrough
backed by overlayfs), user_file may itself be a backing file. Its
fsec->sid is the SID of the mounter that opened it, rather than the user
that opened the top-level file. mprotect() then checks fd { use } against
the mounter SID. This can incorrectly deny access without a domain
transition, or check the wrong target SID after one.
Copy the saved user SID when user_file is a backing file. Keep using the
regular file SID for the first backing layer.
With two nested overlayfs mounts and SELinux enforcing,
mprotect(PROT_READ) returns EACCES with an fd { use } denial against the
mounter SID. With this change, mprotect() succeeds.
Tested on arm64 QEMU with a small BusyBox initramfs and a purpose-built
SELinux policy. The original test was also repeated with Fedora Cloud
Base 44 userspace and gave the same result.
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