# CVE-2024-36489: tls: fix missing memory barrier in tls_init

> A missing memory barrier in the Linux kernel TLS initialization can lead to a NULL pointer dereference, causing a denial of service.

- **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:** 21 Jun 2024
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2024-36489, DEBIAN-CVE-2024-36489, GHSA-692g-7998-j2vj, UBUNTU-CVE-2024-36489

## What is CVE-2024-36489?

CVE-2024-36489 is a medium-severity vulnerability in Linux kernel, published on 21 Jun 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:

tls: fix missing memory barrier in tls_init

In tls_init(), a write memory barrier is missing, and store-store
reordering may cause NULL dereference in tls_{setsockopt,getsockopt}.

CPU0                               CPU1
-----                              -----
// In tls_init()
// In tls_ctx_create()
ctx = kzalloc()
ctx->sk_proto = READ_ONCE(sk->sk_prot) -(1)

// In update_sk_prot()
WRITE_ONCE(sk->sk_prot, tls_prots)     -(2)

                                   // In sock_common_setsockopt()
                                   READ_ONCE(sk->sk_prot)->setsockopt()

                                   // In tls_{setsockopt,getsockopt}()
                                   ctx->sk_proto->setsockopt()    -(3)

In the above scenario, when (1) and (2) are reordered, (3) can observe
the NULL value of ctx->sk_proto, causing NULL dereference.

To fix it, we rely on rcu_assign_pointer() which implies the release
barrier semantic. By moving rcu_assign_pointer() after ctx->sk_proto is
initialized, we can ensure that ctx->sk_proto are visible when
changing sk->sk_prot.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2024-36489?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-36489?

Apply the vendor's patch.

## Is CVE-2024-36489 being exploited?

There is no known exploitation of CVE-2024-36489 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-2024-36489 and fix it if it is affected.

What it is: CVE-2024-36489 is a medium-severity vulnerability in Linux kernel, published on 21 Jun 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-2024-36489 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-2024-36489/ (Markdown: https://insights.sbomify.com/CVE-2024-36489/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-36489
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-36489
- OSV: https://osv.dev/vulnerability/CVE-2024-36489

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-36489/
Summaries are generated and may contain mistakes; the official description above is the record.