CVE-2026-72340
CVE-2026-72340 is a security vulnerability. O3 Security confirms whether CVE-2026-72340 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
In the Linux kernel, the following vulnerability has been resolved: net: microchip: vcap: fix races on the shared Super VCAP block The VCAP instances on a chip are not independent,…
Description
In the Linux kernel, the following vulnerability has been resolved:
net: microchip: vcap: fix races on the shared Super VCAP block
The VCAP instances on a chip are not independent, yet they are locked independently. On sparx5 and lan969x the IS0 and IS2 instances are backed by the same Super VCAP hardware block and share its cache and command registers: every access drives the shared VCAP_SUPER_CTRL register and moves data through the shared cache registers.
Accessing one instance therefore races with accessing another. The per-instance admin->lock cannot prevent this, as each instance takes a different lock.
The locking issue is mostly disguised by the fact that the core usage of the vcap api runs under rtnl. However, the full rule dump in debugfs decodes rules straight from hardware (a READ command followed by a cache read) and runs outside rtnl, so it races a concurrent tc-flower rule write to another Super VCAP instance.
Besides corrupting the dump, the read repopulates the shared cache between the writers cache fill and its write command, so the writer commits the wrong data and corrupts the hardware entry.
Introduce vcap_lock() and vcap_unlock() helpers and route every rule lock site in the VCAP API and its debugfs code through them. Replace the per-instance admin->lock with a single mutex in struct vcap_control that serializes access to all instances. The helpers reach it through a new admin->vctrl back-pointer, and the clients initialise and destroy the control lock instead of a per-instance one.
No path holds more than one instance lock, so collapsing them onto a single mutex cannot self-deadlock.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. 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.
Remediation status
No patched version of the affected component has shipped for CVE-2026-72340 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
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-2026-72340 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-2026-72340. 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-2026-72340 in your dependencies?
O3 detects CVE-2026-72340 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.