bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
CVE-2026-23383 · published 25 Mar 2026
How serious is it
- Severity: high, CVSS score 7.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-23383?
Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.
Who is affected
- Linux Linux: b2ad54e1533e91449cb2a371e034942bd7882b58 to < f5a41b61b5faae1965a5a2cb55322fe8f17e3b2d, b2ad54e1533e91449cb2a371e034942bd7882b58 to < 80ad264da02cc4aee718e799c2b79f0f834673dc, b2ad54e1533e91449cb2a371e034942bd7882b58 to < 519b1ad91de5bf7a496f2b858e9212db6328e1de, b2ad54e1533e91449cb2a371e034942bd7882b58 to < 66959ed481a474eaae278c7f6860a2a9b188a4d6
- Linux Linux: 6.0
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing
struct bpf_plt contains a u64 target field. Currently, the BPF JIT
allocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT
buffer.
Because the base address of the JIT buffer can be 4-byte aligned (e.g.,
ending in 0x4 or 0xc), the relative padding logic in build_plt() fails
to ensure that target lands on an 8-byte boundary.
This leads to two issues:
1. UBSAN reports misaligned-access warnings when dereferencing the
structure.
2. More critically, target is updated concurrently via WRITE_ONCE() in
bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64,
64-bit loads/stores are only guaranteed to be single-copy atomic if
they are 64-bit aligned. A misaligned target risks a torn read,
causing the JIT to jump to a corrupted address.
Fix this by increasing the allocation alignment requirement to 8 bytes
(sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of
the JIT buffer to an 8-byte boundary, allowing the relative padding math
in build_plt() to correctly align the target field.
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
- git.kernel.org/stable/c/f5a41b61b5faae1965a5a2cb55322fe8f17e3b2d
- git.kernel.org/stable/c/80ad264da02cc4aee718e799c2b79f0f834673dc
- git.kernel.org/stable/c/519b1ad91de5bf7a496f2b858e9212db6328e1de
- git.kernel.org/stable/c/66959ed481a474eaae278c7f6860a2a9b188a4d6
- git.kernel.org/stable/c/ef06fd16d48704eac868441d98d4ef083d8f3d07
Merged from CVE List. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON