CVE-2026-43106 cachefiles: fix incorrect dentry refcount in cachefiles_cull()
A reference counting error in the Linux kernel's cachefiles module can lead to use-after-free conditions, potentially causing system crashes or arbitrary code execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-43106?
CVE-2026-43106 is a high-severity use after free vulnerability in Linux kernel, published on 6 May 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
cachefiles: fix incorrect dentry refcount in cachefiles_cull()
The patch mentioned below changed cachefiles_bury_object() to expect 2 references to the 'rep' dentry. Three of the callers were changed to use start_removing_dentry() which takes an extra reference so in those cases the call gets the expected references.
However there is another call to cachefiles_bury_object() in cachefiles_cull() which did not need to be changed to use start_removing_dentry() and so was not properly considered. It still passed the dentry with just one reference so the net result is that a reference is lost.
To meet the expectations of cachefiles_bury_object(), cachefiles_cull() must take an extra reference before the call. It will be dropped by cachefiles_bury_object().
Which versions are affected by CVE-2026-43106?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-43106?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-43106 being exploited?
There is no known exploitation of CVE-2026-43106 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as DEBIAN-CVE-2026-43106, GHSA-frxf-jp28-379q, UBUNTU-CVE-2026-43106.