How severe is CVE-2026-64235?

CVE-2026-64235 has a CVSS score of 8.1/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-64235?

CVE-2026-64235 affects the following packages: Kernel (Linux). Ecosystems affected: Linux.

How do I fix CVE-2026-64235?

Update Kernel to 6.12.93 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-64235 is resolved across your whole dependency graph.

How do I detect CVE-2026-64235 in my Linux dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Kernel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-64235 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-64235?

O3 pinpoints whether CVE-2026-64235 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-64235 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-64235 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was CVE-2026-64235 published, and has it been updated?

CVE-2026-64235 was published on July 24, 2026 and was last updated on August 1, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐧 Linux

CVE-2026-64235

HIGH

CVE-2026-64235 is a high-severity (CVSS 8.1) vulnerability in Kernel. O3 Security confirms whether CVE-2026-64235 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

x86/ftrace: Relocate %rip-relative percpu refs in dynamic trampolines

Published

Jul 24, 2026

Updated

Aug 1, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Blast Radius

1 pkg affected

🐧Kernel

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Linux packages — download data is not available via public APIs for these ecosystems.

Description

In the Linux kernel, the following vulnerability has been resolved:

x86/ftrace: Relocate %rip-relative percpu refs in dynamic trampolines

With CONFIG_CALL_DEPTH_TRACKING enabled on an x86 retbleed-affected platform (eg: Skylake), with retbleed=stuff, registering a dynamic ftrace trampoline crashes on the first call into the traced function:

BUG: unable to handle page fault for address: ffff88817ae18880 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 4b53067 P4D 4b53067 PUD 0 Oops: Oops: 0002 [#1] SMP PTI CPU: 3 UID: 0 PID: 187 Comm: usleep Not tainted 7.0.10 #243 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.17.0-2-2 04/01/2014 Code: 24 78 00 00 00 00 48 89 ea 48 89 54 24 20 48 8b b4 24 b8 00 00 00 48 8b bc 24 b0 00 00 00 48 89 bc 24 80 00 00 00 48 83 ef 05 <65> 48 c1 3d 1f a8 b6 02 05 48 8b 15 f6 00 00 00 4c 89 3c 24 4c 89 Call Trace: <TASK> ? find_held_lock ? exc_page_fault ? lock_release ? __x64_sys_clock_nanosleep ? lockdep_hardirqs_on_prepare ? trace_hardirqs_on __x64_sys_clock_nanosleep do_syscall_64 ? exc_page_fault ? call_depth_return_thunk entry_SYSCALL_64_after_hwframe ... Kernel panic - not syncing: Fatal exception

This small reproducer allows to easily trigger the crash:

echo 'p __x64_sys_clock_nanosleep' > /sys/kernel/tracing/kprobe_events

echo 1 > /sys/kernel/tracing/events/kprobes/p___x64_sys_clock_nanosleep_0/enable

usleep 1

Monitoring the crash under GDB points to the exact instruction in charge of incrementing the call depth:

sarq $5, %gs:__x86_call_depth(%rip)

This instruction matches the one inserted by the ftrace_regs_caller from ftrace_64.S. This emitted code was likely working fine until the introduction of

59bec00ace28 ("x86/percpu: Introduce %rip-relative addressing to PER_CPU_VAR()"):

it has made the call depth accounting addressing relative to $rip, instead of being based on an absolute address.

As this code exact location depends on where the trampoline lives in memory, the corresponding displacement needs to be adjusted at runtime to actually correctly find the per-cpu __x86_call_depth value, otherwise the targeted address is wrong, leading to the page fault seen above.

Fix the %rip-relative displacement of the copied CALL_DEPTH_ACCOUNT instruction (from ftrace_regs_caller) by calling text_poke_apply_relocation(), as it is done for example by the x86 BPF JIT compiler through x86_call_depth_emit_accounting(). This corrects both CALL_DEPTH_ACCOUNT slots, in ftrace_caller and ftrace_regs_caller.

[ bp: Massage. ]

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐧Linux	`Kernel`	≥ 6.9.0&&< 6.12.93	6.12.93

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Kernel. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update Kernel to 6.12.93 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-64235 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-64235 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-64235. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

In the Linux kernel, the following vulnerability has been resolved: x86/ftrace: Relocate %rip-relative percpu refs in dynamic trampolines With CONFIG_CALL_DEPTH_TRACKING enabled on an x86 retbleed-affected platform (eg: Skylake), with retbleed=stuff, registering a dynamic ftrace trampoline crashes on the first call into the traced function: BUG: unable to handle page fault for address: ffff88817ae18880 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD 4b53067 P4D 4b53067 PUD 0 Oops: Oops: 0002 [#1] SMP PTI CPU: 3 UID: 0 PID: 187 Comm: usl

O3 Security · Impact-Aware SCA

Is CVE-2026-64235 in your dependencies?

O3 detects CVE-2026-64235 across Linux dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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