# CVE-2019-9213: Null dereference in n/a

> Missing address check in Linux kernel allows attackers to exploit NULL pointer dereferences for privilege escalation on non-SMAP platforms.

- **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:** 5 Mar 2019
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2019-9213, GHSA-4r7r-87cf-rc4r, MGASA-2019-0120, SUSE-SU-2019:0761-1, UBUNTU-CVE-2019-9213

## What is CVE-2019-9213?

CVE-2019-9213 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 5 Mar 2019. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel before 4.20.14, expand_downwards in mm/mmap.c lacks a check for the mmap minimum address, which makes it easier for attackers to exploit kernel NULL pointer dereferences on non-SMAP platforms. This is related to a capability check for the wrong task.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2019-9213?

It affects 5 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `kgraft-patch-SLE12-SP3_Update_23` | SUSE:Linux Enterprise Live Patching 12 SP3 | All versions | 2-2.1 |

Products: Canonical Ubuntu Linux, Debian Debian Linux, Linux kernel, Opensuse Leap, Redhat Enterprise Linux.

## How do I fix CVE-2019-9213?

Apply the vendor's patch.

## Is CVE-2019-9213 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2019-9213 exists.

Public exploit code:

- Reliable Datagram Sockets (RDS) rds_atomic_free_op NULL pointer dereference Privilege Escalation (metasploit)
- Linux < 4.20.14 - Virtual Address 0 is Mappable via Privileged write() to /proc/*/mem (exploitdb)
- Reliable Datagram Sockets (RDS) - rds_atomic_free_op NULL pointer dereference Privilege Escalation (Metasploit) (exploitdb)
- Reliable Datagram Sockets (RDS) - rds_atomic_free_op NULL pointer dereference Privilege Escalation (Metasploit) (exploitdb)

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-9213 and fix it if it is affected.

What it is: CVE-2019-9213 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 5 Mar 2019. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2019-9213 exists.

Affected product: Canonical Ubuntu Linux. 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-2019-9213/ (Markdown: https://insights.sbomify.com/CVE-2019-9213/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-9213
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-9213
- OSV: https://osv.dev/vulnerability/CVE-2019-9213

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-9213/
Summaries are generated and may contain mistakes; the official description above is the record.