CVE-2026-90326 — Kernel
HIGHCVE-2026-90326 is a high-severity (CVSS 7.8) vulnerability in Kernel. A fix is available for Kernel — see the affected versions and patch details below.
blk-cgroup: fix race between policy activation and blkg destruction
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-90326 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 374,847 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
KernelReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Linux packages — download data is not available via public APIs for these ecosystems.
Description
In the Linux kernel, the following vulnerability has been resolved:
blk-cgroup: fix race between policy activation and blkg destruction
When switching an IO scheduler on a block device, blkcg_activate_policy() allocates blkg_policy_data (pd) for all blkgs attached to the queue. However, blkcg_activate_policy() may race with concurrent blkcg deletion, leading to use-after-free and memory leak issues.
The use-after-free occurs in the following race:
T1 (blkcg_activate_policy):
- Successfully allocates pd for blkg1 (loop0->queue, blkcgA)
- Fails to allocate pd for blkg2 (loop0->queue, blkcgB)
- Enters the enomem rollback path to release blkg1 resources
T2 (blkcg deletion):
- blkcgA is deleted concurrently
- blkg1 is freed via blkg_free_workfn()
- blkg1->pd is freed
T1 (continued):
- Rollback path accesses blkg1->pd->online after pd is freed
- Triggers use-after-free
In addition, blkg_free_workfn() frees pd before removing the blkg from q->blkg_list. This allows blkcg_activate_policy() to allocate a new pd for a blkg that is being destroyed, leaving the newly allocated pd unreachable when the blkg is finally freed.
Fix these races by extending blkcg_mutex coverage to serialize blkcg_activate_policy() rollback and blkg destruction, ensuring pd lifecycle is synchronized with blkg list visibility.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐧Linux | Kernel | ≥ 6.2.0&&< 6.1.17 | 6.1.17 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Kernel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update Kernel to 6.1.17 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-90326 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-90326 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-90326. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-90326 in your dependencies?
O3 Security finds CVE-2026-90326 across Linux dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.