CVE-2026-64507: x86/bugs: Enable IBPB flush on BPF JIT allocation
In the Linux kernel, the following vulnerability has been resolved:
x86/bugs: Enable IBPB flush on BPF JIT allocation
Enable hardening against JIT spraying when Spectre-v2 mitigations are in use. Specifically, issue an IBPB flush on BPF JIT memory reuse. Skip enabling the IBPB flush if the BPF dispatcher is already using a retpoline sequence.
This hardening applies only when BPF-JIT is in use. Guard the enabling under CONFIGBPFJIT so that bugs.c still builds with CONFIGBPFJIT=n.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 6.6.145.2-1 - Configuration
Enable CONFIG_BPF_JIT so that the IBPB flush hardening for BPF JIT allocation is built and applied (note: ensure bugs.c still builds with CONFIG_BPF_JIT=n).
Linux kernel CONFIG_BPF_JIT = y - Configuration
Harden against JIT spraying with Spectre-v2 mitigations by issuing an IBPB flush on BPF JIT memory reuse/allocation when BPF-JIT is in use and the BPF dispatcher is already using a retpoline sequence.
Linux kernel (x86/bugs: BPF JIT) IBPB flush on BPF JIT allocation (IBPB flush / dispatcher retpoline state) = enabled when BPF-JIT is in use and the BPF dispatcher is already using a retpoline sequence
Event History
Frequently Asked Questions
What is the severity of CVE-2026-64507?
CVE-2026-64507 has a risk rating of 37, indicating a moderate severity vulnerability.
How does CVE-2026-64507 impact the Linux kernel?
CVE-2026-64507 enables IBPB flush on BPF JIT allocation, enhancing security against JIT spraying with Spectre-v2 mitigations.
How do I fix CVE-2026-64507?
To fix CVE-2026-64507, update to the latest version of the Linux kernel where the vulnerability has been resolved.
What are the symptoms of exploiting CVE-2026-64507?
Exploitation of CVE-2026-64507 may lead to increased risk of side-channel attacks through JIT memory reuse.
In which versions of Linux kernel does CVE-2026-64507 exist?
CVE-2026-64507 exists in affected versions of the Linux kernel prior to the resolution implemented on July 25, 2026.