# CVE-2024-42063: bpf: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode

> A local attacker with BPF privileges can read uninitialized kernel stack memory via BPF map operations in interpreter mode, potentially leaking sensitive data.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 29 Jul 2024
- **Updated:** 11 May 2026
- **Also known as:** AZL-48656, BELL-CVE-2024-42063, DEBIAN-CVE-2024-42063, GHSA-8ghr-4wgh-3jq8, ROOT-OS-DEBIAN-11-CVE-2024-42063, UBUNTU-CVE-2024-42063

## What is CVE-2024-42063?

CVE-2024-42063 is a medium-severity vulnerability in Linux kernel, published on 29 Jul 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: Mark bpf prog stack with kmsan_unposion_memory in interpreter mode

syzbot reported uninit memory usages during map_{lookup,delete}_elem.

==========
BUG: KMSAN: uninit-value in __dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline]
BUG: KMSAN: uninit-value in dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796
__dev_map_lookup_elem kernel/bpf/devmap.c:441 [inline]
dev_map_lookup_elem+0xf3/0x170 kernel/bpf/devmap.c:796
____bpf_map_lookup_elem kernel/bpf/helpers.c:42 [inline]
bpf_map_lookup_elem+0x5c/0x80 kernel/bpf/helpers.c:38
___bpf_prog_run+0x13fe/0xe0f0 kernel/bpf/core.c:1997
__bpf_prog_run256+0xb5/0xe0 kernel/bpf/core.c:2237
==========

The reproducer should be in the interpreter mode.

The C reproducer is trying to run the following bpf prog:

    0: (18) r0 = 0x0
    2: (18) r1 = map[id:49]
    4: (b7) r8 = 16777216
    5: (7b) *(u64 *)(r10 -8) = r8
    6: (bf) r2 = r10
    7: (07) r2 += -229
            ^^^^^^^^^^

    8: (b7) r3 = 8
    9: (b7) r4 = 0
   10: (85) call dev_map_lookup_elem#1543472
   11: (95) exit

It is due to the "void *key" (r2) passed to the helper. bpf allows uninit
stack memory access for bpf prog with the right privileges. This patch
uses kmsan_unpoison_memory() to mark the stack as initialized.

This should address different syzbot reports on the uninit "void *key"
argument during map_{lookup,delete}_elem.

Weakness: CWE-908 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2024-42063?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-42063?

Apply the vendor's patch.

## Is CVE-2024-42063 being exploited?

There is no known exploitation of CVE-2024-42063 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-2024-42063 and fix it if it is affected.

What it is: CVE-2024-42063 is a medium-severity vulnerability in Linux kernel, published on 29 Jul 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-2024-42063 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-2024-42063/ (Markdown: https://insights.sbomify.com/CVE-2024-42063/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-42063
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-42063
- OSV: https://osv.dev/vulnerability/CVE-2024-42063

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-42063/
Summaries are generated and may contain mistakes; the official description above is the record.