# CVE-2024-50164: bpf: Fix overloading of MEM_UNINIT's meaning

> A BPF verifier flaw allows unprivileged programs to write to read-only memory regions, bypassing intended access controls.

- **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:** 7 Nov 2024
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-53561, BELL-CVE-2024-50164, DEBIAN-CVE-2024-50164, GHSA-h38j-rxrv-q3q6, ROOT-OS-UBUNTU-2204-CVE-2024-50164, UBUNTU-CVE-2024-50164

## What is CVE-2024-50164?

CVE-2024-50164 is a high-severity missing authorization vulnerability in Linux kernel, published on 7 Nov 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: Fix overloading of MEM_UNINIT's meaning

Lonial reported an issue in the BPF verifier where check_mem_size_reg()
has the following code:

    if (!tnum_is_const(reg->var_off))
        /* For unprivileged variable accesses, disable raw
         * mode so that the program is required to
         * initialize all the memory that the helper could
         * just partially fill up.
         */
         meta = NULL;

This means that writes are not checked when the register containing the
size of the passed buffer has not a fixed size. Through this bug, a BPF
program can write to a map which is marked as read-only, for example,
.rodata global maps.

The problem is that MEM_UNINIT's initial meaning that "the passed buffer
to the BPF helper does not need to be initialized" which was added back
in commit 435faee1aae9 ("bpf, verifier: add ARG_PTR_TO_RAW_STACK type")
got overloaded over time with "the passed buffer is being written to".

The problem however is that checks such as the above which were added later
via 06c1c049721a ("bpf: allow helpers access to variable memory") set meta
to NULL in order force the user to always initialize the passed buffer to
the helper. Due to the current double meaning of MEM_UNINIT, this bypasses
verifier write checks to the memory (not boundary checks though) and only
assumes the latter memory is read instead.

Fix this by reverting MEM_UNINIT back to its original meaning, and having
MEM_WRITE as an annotation to BPF helpers in order to then trigger the
BPF verifier checks for writing to memory.

Some notes: check_arg_pair_ok() ensures that for ARG_CONST_SIZE{,_OR_ZERO}
we can access fn->arg_type[arg - 1] since it must contain a preceding
ARG_PTR_TO_MEM. For check_mem_reg() the meta argument can be removed
altogether since we do check both BPF_READ and BPF_WRITE. Same for the
equivalent check_kfunc_mem_size_reg().

## Which versions are affected by CVE-2024-50164?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-50164?

Apply the vendor's patch.

## Is CVE-2024-50164 being exploited?

There is no known exploitation of CVE-2024-50164 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-2024-50164 and fix it if it is affected.

What it is: CVE-2024-50164 is a high-severity missing authorization vulnerability in Linux kernel, published on 7 Nov 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-2024-50164 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-2024-50164/ (Markdown: https://insights.sbomify.com/CVE-2024-50164/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-50164
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-50164
- OSV: https://osv.dev/vulnerability/CVE-2024-50164

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-50164/
Summaries are generated and may contain mistakes; the official description above is the record.