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Linux KernelOperating system · Linux

CVE-2023-53634

MEDIUM · 5.5 CVSS v3.1 Published 2025-10-07
Fix available
A fix is available. Upgrade to 6.1.25 / 6.2.12 or later.
See remediation →
57/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: bpf, arm64: Fixed a BTI error on returning to patched function When BPF_TRAMP_F_CALL_ORIG is set, BPF trampoline uses BLR to jump back to the instruction next to call site to call the patched function. For BTI-enabled kernel, the instruction next to call site is usually PACIASP, in this case, it's safe to jump back with BLR. But when the call site is not followed by a PACIASP or bti, a BTI exception is triggered. Here is a fault log: Unhandled 64-bit el1h sync exception on CPU0, ESR 0x0000000034000002 -- BTI CPU: 0 PID: 263 Comm: test_progs Tainted: GF Hardware name: linux,dummy-virt (DT) pstate: 40400805 (nZcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=-c) pc : bpf_fentry_test1+0xc/0x30 lr : bpf_trampoline_6442573892_0+0x48/0x1000 sp : ffff80000c0c3a50 x29: ffff80000c0c3a90 x28: ffff0000c2e6c080 x27: 0000000000000000 x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000050 x23: 0000000000000000 x22: 0000ffffcfd2a7f0 x21: 000000000000000a x20: 0000ffffcfd2a7f0 x19: 0000000000000000 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000ffffcfd2a7f0 x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: ffff80000914f5e4 x9 : ffff8000082a1528 x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0101010101010101 x5 : 0000000000000000 x4 : 00000000fffffff2 x3 : 0000000000000001 x2 : ffff8001f4b82000 x1 : 0000000000000000 x0 : 0000000000000001 Kernel panic - not syncing: Unhandled exception CPU: 0 PID: 263 Comm: test_progs Tainted: GF Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0xec/0x144 show_stack+0x24/0x7c dump_stack_lvl+0x8c/0xb8 dump_stack+0x18/0x34 panic+0x1cc/0x3ec __el0_error_handler_common+0x0/0x130 el1h_64_sync_handler+0x60/0xd0 el1h_64_sync+0x78/0x7c bpf_fentry_test1+0xc/0x30 bpf_fentry_test1+0xc/0x30 bpf_prog_test_run_tracing+0xdc/0x2a0 __sys_bpf+0x438/0x22a0 __arm64_sys_bpf+0x30/0x54 invoke_syscall+0x78/0x110 el0_svc_common.constprop.0+0x6c/0x1d0 do_el0_svc+0x38/0xe0 el0_svc+0x30/0xd0 el0t_64_sync_handler+0x1ac/0x1b0 el0t_64_sync+0x1a0/0x1a4 Kernel Offset: disabled CPU features: 0x0000,00034c24,f994fdab Memory Limit: none And the instruction next to call site of bpf_fentry_test1 is ADD, not PACIASP: <bpf_fentry_test1>: bti c nop nop add w0, w0, #0x1 paciasp For BPF prog, JIT always puts a PACIASP after call site for BTI-enabled kernel, so there is no problem. To fix it, replace BLR with RET to bypass the branch target check.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis

A detailed technical summary for this CVE is being prepared.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 6.0, < 6.1.25>= 6.2, < 6.2.12= 6.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 6.1.25 / 6.2.12 or later
Fixed in 6.1.256.2.12
Vendor patch git.kernel.org →
Recommended fix High confidence

6.1.25+ (for 6.1.x), 6.2.12+ (for 6.2.x), or 6.4+ (for 6.3.x)

  1. Identify the current kernel version using 'uname -r' or 'cat /proc/version'
  2. Determine if the version is affected: 6.0 to <6.1.25, 6.2 to <6.2.12, or exactly 6.3
  3. For kernels 6.1.x: upgrade to kernel version 6.1.25 or later
  4. For kernels 6.2.x: upgrade to kernel version 6.2.12 or later
  5. For kernel 6.3.x: upgrade to kernel version 6.4 or later
  6. Obtain the updated kernel package from your distribution's official repositories (e.g., apt update && apt install linux-image, yum update kernel, dnf update kernel, or distribution-specific equivalent)
  7. Reboot the system into the new kernel to apply the fix
Caveat Kernel upgrades may require system reboot and could have driver compatibility implications; test in staging if possible

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-53634 in production — separate from our analysis above.

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