# CVE-2021-38604: Null dereference in n/a

> A NULL pointer dereference in glibc's librt allows attackers to cause a denial of service via mishandled NOTIFY_REMOVED data.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Aug 2021
- **Updated:** 14 Oct 2026
- **Also known as:** AZL-6442, GHSA-p3v7-wjmc-7fh8, MGASA-2021-0404, MINI-2x36-mg47-wp3p, OESA-2021-1328

## What is CVE-2021-38604?

CVE-2021-38604 is a high-severity vulnerability in Fedoraproject Fedora, published on 12 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

In librt in the GNU C Library (aka glibc) through 2.34, sysdeps/unix/sysv/linux/mq_notify.c mishandles certain NOTIFY_REMOVED data, leading to a NULL pointer dereference. NOTE: this vulnerability was introduced as a side effect of the CVE-2021-33574 fix.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-38604?

It affects 8 products.


Products: Fedoraproject Fedora, Gnu Glibc, Oracle Communications Cloud Native Core Binding Support Function, Oracle Communications Cloud Native Core Network Function Cloud Native Environment, Oracle Communications Cloud Native Core Network Repository Function, Oracle Communications Cloud Native Core Security Edge Protection Proxy, Oracle Communications Cloud Native Core Unified Data Repository, Oracle Enterprise Operations Monitor.

## How do I fix CVE-2021-38604?

Apply the vendor's patch.

## Is CVE-2021-38604 being exploited?

There is no known exploitation of CVE-2021-38604 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2024-4577](https://insights.sbomify.com/CVE-2024-4577/): PHP-CGI OS Command Injection (critical 9.8, exploited in the wild)
- [CVE-2021-39226](https://insights.sbomify.com/CVE-2021-39226/): Grafana Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2019-5544](https://insights.sbomify.com/CVE-2019-5544/): VMware ESXi and Horizon DaaS OpenSLP Heap-Based Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2024-4947](https://insights.sbomify.com/CVE-2024-4947/): Google Chromium V8 Type Confusion (critical 9.6, exploited in the wild)
- [CVE-2024-4671](https://insights.sbomify.com/CVE-2024-4671/): Google Chromium Visuals Use-After-Free (critical 9.6, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-38604 and fix it if it is affected.

What it is: CVE-2021-38604 is a high-severity vulnerability in Fedoraproject Fedora, published on 12 Aug 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-38604 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2021-38604/ (Markdown: https://insights.sbomify.com/CVE-2021-38604/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-38604
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-38604
- OSV: https://osv.dev/vulnerability/CVE-2021-38604

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-38604/
Summaries are generated and may contain mistakes; the official description above is the record.