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.
CVE-2026-98215
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-98215
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "bc6c380c1159de52a252ed11f19a42c47f60a735",
"lessThan": "caa1b913d90d5dc07073733326d2af0f0288f089",
"versionType": "git"
},
{
"status": "affected",
"version": "8bacd09f12c27710228562e4d13163e58c5f4a45",
"lessThan": "6aaeec59aadcd1eafc18b049f1b759fb6b9d9569",
"versionType": "git"
},
{
"status": "affected",
"version": "d844702198395d3f80222777030f69db6be6b709",
"lessThan": "9d99b770e7b67b00bdef9005b928aad13e1d679b",
"versionType": "git"
},
{
"status": "affected",
"version": "82544d36b1729153c8aeb179e84750f0c085d3b1",
"lessThan": "ff20d16b2e8230c034e21540043df47222dcc09b",
"versionType": "git"
},
{
"status": "affected",
"version": "82544d36b1729153c8aeb179e84750f0c085d3b1",
"lessThan": "8c0c602202b9a4909b00bc3354e3c0355bc69e65",
"versionType": "git"
},
{
"status": "affected",
"version": "cd0e707a927a70cdfd8bc5a512a9719a87f5ed51",
"versionType": "git"
},
{
"status": "affected",
"version": "6.6.144",
"lessThan": "6.6.158",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.12.95",
"lessThan": "6.12.112",
"versionType": "semver"
},
{
"status": "affected",
"version": "6.18.38",
"lessThan": "6.18.54",
"versionType": "semver"
},
{
"status": "affected",
"version": "7.0.4",
"lessThan": "7.1",
"versionType": "semver"
}
],
"programFiles": [
"security/selinux/hooks.c",
"security/selinux/include/objsec.h"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "7.1"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "7.1",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.112",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.54",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.8",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"security/selinux/hooks.c",
"security/selinux/include/objsec.h"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98215
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #38297 · Revision 1
- Added to Heist Feed
- Publisher date