# CVE-2024-53125: bpf: sync_linked_regs() must preserve subreg_def

> A flaw in the Linux kernel BPF verifier allows incorrect code rewriting when specific flags are set, potentially leading to arbitrary code execution.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 4 Dec 2024
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2024-53125, DEBIAN-CVE-2024-53125, GHSA-jgf3-fmmf-vj4h, UBUNTU-CVE-2024-53125

## What is CVE-2024-53125?

CVE-2024-53125 is a high-severity vulnerability in Linux kernel, published on 4 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

bpf: sync_linked_regs() must preserve subreg_def

Range propagation must not affect subreg_def marks, otherwise the
following example is rewritten by verifier incorrectly when
BPF_F_TEST_RND_HI32 flag is set:

  0: call bpf_ktime_get_ns                   call bpf_ktime_get_ns
  1: r0 &= 0x7fffffff       after verifier   r0 &= 0x7fffffff
  2: w1 = w0                rewrites         w1 = w0
  3: if w0 < 10 goto +0     -------------->  r11 = 0x2f5674a6     (r)
  4: r1 >>= 32                               r11 <<= 32           (r)
  5: r0 = r1                                 r1 |= r11            (r)
  6: exit;                                   if w0 < 0xa goto pc+0
                                             r1 >>= 32
                                             r0 = r1
                                             exit

(or zero extension of w1 at (2) is missing for architectures that
 require zero extension for upper register half).

The following happens w/o this patch:
- r0 is marked as not a subreg at (0);
- w1 is marked as subreg at (2);
- w1 subreg_def is overridden at (3) by copy_register_state();
- w1 is read at (5) but mark_insn_zext() does not mark (2)
  for zero extension, because w1 subreg_def is not set;
- because of BPF_F_TEST_RND_HI32 flag verifier inserts random
  value for hi32 bits of (2) (marked (r));
- this random value is read at (5).

## Which versions are affected by CVE-2024-53125?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-53125?

Apply the vendor's patch.

## Is CVE-2024-53125 being exploited?

There is no known exploitation of CVE-2024-53125 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2024-53125 and fix it if it is affected.

What it is: CVE-2024-53125 is a high-severity vulnerability in Linux kernel, published on 4 Dec 2024. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-53125 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2024-53125/ (Markdown: https://insights.sbomify.com/CVE-2024-53125/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-53125
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-53125
- OSV: https://osv.dev/vulnerability/CVE-2024-53125

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-53125/
Summaries are generated and may contain mistakes; the official description above is the record.