CVE-2026-64467 rust_binder: use a u64 stride when cleaning up the offsets array
A stride mismatch in the Linux kernel's Rust binder driver causes refcount underflows on 32-bit systems, leading to potential denial of service.
- 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-2026-64467?
CVE-2026-64467 is a high-severity vulnerability in Linux, published on 25 Jul 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:
rust_binder: use a u64 stride when cleaning up the offsets array
Allocation's Drop walks the offsets array (binder_size_t = u64 entries), cleaning up the objects, but it used usize instead of u64 for both the stride and the per-entry read.
On 64-bit kernels (usize == u64) this is harmless, but on 32-bit kernels it walks the 8-byte entries in 4-byte steps, iterating an N-entry array 2N times, and reads the always-zero high word as offset 0, cleaning up the object at offset 0 N extra times. As a result the referenced node or handle ends up with a lower reference count than it actually has (a refcount over-decrement), and binder's reference accounting is corrupted; for example, the owner can be notified of a strong reference release (BR_RELEASE) even though references still remain.
Change the stride to u64, and read each entry as a u64, narrowing it to usize with try_into().
On 32-bit ARM, when this over-decrement would drive a count below zero, the driver's existing refcount guard refuses it and fires:
rust_binder: Failure: refcount underflow!
Which versions are affected by CVE-2026-64467?
How do I fix CVE-2026-64467?
Apply the vendor's patch.
Is CVE-2026-64467 being exploited?
There is no known exploitation of CVE-2026-64467 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64467, DEBIAN-CVE-2026-64467, GHSA-jcch-xvf6-72qc, ROOT-OS-UBUNTU-2204-CVE-2026-64467, UBUNTU-CVE-2026-64467.