Bug 2507153 (CVE-2026-64508)

Summary: CVE-2026-64508 kernel: bpf: Support for hardening against JIT spraying
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Berkeley Packet Filter (BPF) Just-In-Time (JIT) compiler. The BPF JIT allocator reuses memory space, and when new code is written, an indirect jump into the new program can reuse a branch prediction left behind by an old program. This could allow an attacker to bypass security hardening mechanisms, potentially leading to information disclosure or other impacts. The vulnerability is mitigated by flushing indirect branch predictors before reusing JIT memory.
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Description OSIDB Bzimport 2026-07-25 10:07:50 UTC 
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.
Comment 1 TEJ RATHI 2026-07-29 15:07:01 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072554-CVE-2026-64508-fe26@gregkh/T