CVE-2026-98215
selinux: preserve user SID across nested backing files
No known exploitation. EPSS puts it in the 10th percentile. Fixed versions are out.
What to do
Find your product and version, then upgrade to the build on the right.
- LinuxAffected: ≥ bc6c380c1159de52a252ed11f19a42c47f60a735, < caa1b913d90d5dc07073733326d2af0f0288f089Upgrade to: caa1b913d90d5dc07073733326d2af0f0288f089Affected: ≥ 8bacd09f12c27710228562e4d13163e58c5f4a45, < 6aaeec59aadcd1eafc18b049f1b759fb6b9d9569Upgrade to: 6aaeec59aadcd1eafc18b049f1b759fb6b9d9569Affected: ≥ d844702198395d3f80222777030f69db6be6b709, < 9d99b770e7b67b00bdef9005b928aad13e1d679bUpgrade to: 9d99b770e7b67b00bdef9005b928aad13e1d679bAffected: ≥ 82544d36b1729153c8aeb179e84750f0c085d3b1, < ff20d16b2e8230c034e21540043df47222dcc09bUpgrade to: ff20d16b2e8230c034e21540043df47222dcc09b + 6 more branchesStated by: CVE record
Versions as the sources state them. Full version matrix after sign-in
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.2% chance of exploitation activity in the next 30 days, which ranks it in the 10th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
2 events over 0 days, from the signal feeds we watch.
- Publishedrecord updated
Affected products
Sources
References in the record
- git.kernel.org/stable/c/6aaeec59aadcd1eafc18b049f1b759fb6b9d9569
- git.kernel.org/stable/c/8c0c602202b9a4909b00bc3354e3c0355bc69e65
- git.kernel.org/stable/c/9d99b770e7b67b00bdef9005b928aad13e1d679b
And 2 more references. See all after sign-in
In the news
Watch the software you run.
My Stack ranks new CVEs for your products by real-world exploitation, so the next serious one reaches you without reading every advisory.
We'll flag the next CVE, public exploit or patch for Linux, not every advisory.
A free account adds
- The full version matrix and every affected product
- Exploit links, proofs of concept and Metasploit modules
- Email alerts for the products you watch
- The same data over REST API, MCP and CLI