CVE-2026-72164
CVE-2026-72164 is a security vulnerability in Kernel. O3 Security confirms whether CVE-2026-72164 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
ocfs2: avoid moving extents to occupied clusters
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:
ocfs2: avoid moving extents to occupied clusters
For non-auto OCFS2_IOC_MOVE_EXT operations, userspace supplies a physical me_goal. ocfs2_move_extent() initializes new_phys_cpos from that goal and expects ocfs2_probe_alloc_group() to replace it with a free run in the target block group.
The probe currently leaves *phys_cpos unchanged if the scan reaches the end of the group without finding a free run. An occupied goal at the last bit can therefore survive the probe and be passed to __ocfs2_move_extent(), which copies file data into a cluster still owned by another inode before the bitmap is updated.
When the probe does find a free run, it also subtracts move_len from the ending bit. The start of an N-bit run ending at i is i - N + 1, so the current calculation can report the bit immediately before the free run.
Clear *phys_cpos before scanning and use the correct free-run start. Callers already treat a zero result as -ENOSPC, so failed probes no longer continue with an occupied caller-controlled goal.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐧Linux | Kernel | ≥ 3.0.0&&< 5.10.261 | 5.10.261 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Kernel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update Kernel to 5.10.261 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-72164 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 pinpoints whether CVE-2026-72164 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-72164. 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-2026-72164 in your dependencies?
O3 detects CVE-2026-72164 across Linux dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.