CVE-2026-64508 bpf: Support for hardening against JIT spraying
Attackers can exploit JIT memory reuse to bypass branch predictor hardening, potentially leading to privilege escalation or code execution in the Linux kernel.
- 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-2026-64508?
CVE-2026-64508 is a 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:
bpf: Support for hardening against JIT spraying
The BPF JIT allocator packs many small programs into larger executable allocations and reuses space within those allocations as programs are loaded and freed. When fresh code is written into space that a previous program occupied, an indirect jump into the new program can reuse a branch prediction left behind by the old one.
Flush the indirect branch predictors before reusing JIT memory so that indirect jumps into a newly written program don't reuse predictions from an old program that occupied the same space.
Introduce bpf_arch_pred_flush_enabled static key and bpf_arch_pred_flush static call for flushing the branch predictors on JIT memory reuse. Architectures that need a flush, can update it to a predictor flush function. By default, its a NOP and does not emit any CALL.
Allocations larger than a pack are not covered by this flush. That is safe because cBPF programs (the unprivileged attack surface) are bounded well below a pack size. Issue a warning if this assumption is ever violated while the flush is active.
Which versions are affected by CVE-2026-64508?
How do I fix CVE-2026-64508?
Apply the vendor's patch.
Is CVE-2026-64508 being exploited?
There is no known exploitation of CVE-2026-64508 in the wild and no public exploit code.
Sources
Also known as AZL-93857, BELL-CVE-2026-64508, DEBIAN-CVE-2026-64508, GHSA-667g-8hv2-vmxj, ROOT-OS-UBUNTU-2204-CVE-2026-64508, UBUNTU-CVE-2026-64508.