Read the docs
TI-2026-68106 Aliases CVE-2026-98215GHSA-4rhv-8vqv-p9w9

SELinux in Linux kernel uses wrong SID for nested backing files

Priority LOW 22Published · Updated

Key facts

Attack vector
—
Privileges required
—
User interaction
—
Attack complexity
—
Impact type
—
Confidentiality · integrity · availability
—
Fix status
Partial Red Hat: 6 without a fix

No CVSS vector from any source. Fix status from CNA and Red Hat.

Summary

The Linux kernel SELinux subsystem uses the wrong user SID for nested backing files, such as overlayfs over overlayfs. The saved SID is the mounter's rather than the user's, so mprotect() checks fd use against the wrong SID. A local user with SELinux enforcing can be denied access incorrectly or have access checked against the wrong target SID. Affected ranges include from 6.6.144 before 6.6.158, from 6.12.95 before 6.12.112, from 6.18.38 before 6.18.54 and from 7.0.4 before 7.1.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

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.

Why it matters now

EPSS 0.00206 10th percentileScored 2026-11-07
Fix Partial Linux (Linux): 6.6.158, 6.12.112, 6.18.54 +3Red Hat: 6 without a fix

SSVC decision points

Not available: CISA has not published SSVC decision points for this record.

Affected products

VendorProductAffected versionsFixed inStatusSource
LinuxLinux6.6.144 to before 6.6.158; 6.12.95 to before 6.12.112; 6.18.38 to before 6.18.54; 7.0.4 to before 7.16.6.158, 6.12.112, 6.18.54, 7.1Patch availableCNA
LinuxLinux7.1 and later6.6.158, 6.12.112, 6.18.54, 7.2.8, 7.3Patch availableCNA
  • Linux VendorLinux Affected 6.6.144 to before 6.6.158; 6.12.95 to before 6.12.112; 6.18.38 to before 6.18.54; 7.0.4 to before 7.1 Fixed in 6.6.158, 6.12.112, 6.18.54, 7.1 Patch available CNA
  • Linux VendorLinux Affected 7.1 and later Fixed in 6.6.158, 6.12.112, 6.18.54, 7.2.8, 7.3 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*——Linux
  • cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* Versions — — ·Linux

Remediation

Update the Linux kernel to 6.6.158, 6.12.112, 6.18.54, 7.1, 7.2.8 or 7.3, depending on the branch in use. The sources list no fixed version for Red Hat Enterprise Linux 8, 9 and 10 and OpenShift Container Platform 4 and 5, and no fix planned for Red Hat Enterprise Linux 6.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

  • Fix · CNA Linux (Linux) Fixed in 6.6.158, 6.12.112, 6.18.54, 7.1
  • Fix · CNA Linux (Linux) Fixed in 6.6.158, 6.12.112, 6.18.54, 7.2.8, 7.3

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 6AffectedNo fix planned: Out of support scope
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 4AffectedNo fix yet: Fix deferred
Red Hat OpenShift Container Platform 5AffectedNo fix yet: Fix deferred
Not affected: 1 product
  • Red Hat Enterprise Linux 7

Timeline

  1. 2026-10-06 Threatist record created from CVE-2026-98215
  2. 2026-10-06 Alias added: GHSA-4rhv-8vqv-p9w9
  3. 2026-10-10 Affected versions changed · Red Hat
  4. 2026-10-10 CVSS score added · Red Hat
  5. 2026-10-19 Fix available: Linux/[email protected] · CNA
  6. 2026-10-23 Affected versions changed · Red Hat
  7. 2026-10-23 CVSS score changed · Red Hat
  8. 2026-11-06 Affected versions changed · Red Hat

References

Other 5

  • TI-2025-26358 tls: fix handling of zero-length records on the rx_list KEVCVSS 3.1CRITICAL 9.8
  • TI-2026-38352 netfilter: bridge: make ebt_snat ARP rewrite writable KEVCVSS 3.1HIGH 8.8
  • TI-2021-02452 Incorrect authorization in Ubuntu linux kernel KEVCVSS 3.1HIGH 8.8
  • TI-2013-05264 The (1) get_user and (2) put_user API functions in the Linux kernel before 3.5.5 on the… KEVCVSS 3.1HIGH 8.8
  • TI-2022-00125 Integer overflow in kernel KEVCVSS 3.1HIGH 8.4
  • TI-2013-01864 The perf_swevent_init function in kernel/events/core.c in the Linux kernel before 3.8.9… KEVCVSS 3.1HIGH 8.4
See all 21741 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences