# CVE-2018-1121: Race condition in procps-ng, procps

> An unprivileged attacker can hide processes from system monitoring tools by exploiting a race condition in procps-ng utilities.

- **Severity:** Low 3.9 (`CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 13 Jun 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2018-1121, GHSA-2r59-6pxx-3wqv, ROOT-OS-DEBIAN-12-CVE-2018-1121, ROOT-OS-DEBIAN-13-CVE-2018-1121, ROOT-OS-UBUNTU-2204-CVE-2018-1121, ROOT-OS-UBUNTU-2404-CVE-2018-1121, UBUNTU-CVE-2018-1121

## What is CVE-2018-1121?

CVE-2018-1121 is a low-severity vulnerability in [UNKNOWN] procps-ng, procps, published on 13 Jun 2018. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

procps-ng, procps is vulnerable to a process hiding through race condition. Since the kernel's proc_pid_readdir() returns PID entries in ascending numeric order, a process occupying a high PID can use inotify events to determine when the process list is being scanned, and fork/exec to obtain a lower PID, thus avoiding enumeration. An unprivileged attacker can hide a process from procps-ng's utilities by exploiting a race condition in reading /proc/PID entries. This vulnerability affects procps and procps-ng up to version 3.3.15, newer versions might be affected also.

Weakness: CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization), CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2018-1121?

It affects 1 product.


Products: Procps Project Procps.

## How do I fix CVE-2018-1121?

Apply the vendor's patch.

## Is CVE-2018-1121 being exploited?

There is no known exploitation of CVE-2018-1121 in the wild and no public exploit code.

Public exploit code:

- Procps-ng - Multiple Vulnerabilities (exploitdb)
- Procps-ng - Multiple Vulnerabilities (exploitdb)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2018-1121 and fix it if it is affected.

What it is: CVE-2018-1121 is a low-severity vulnerability in [UNKNOWN] procps-ng, procps, published on 13 Jun 2018. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2018-1121 in the wild and no public exploit code.

Affected product: [UNKNOWN] procps-ng, procps. 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-2018-1121/ (Markdown: https://insights.sbomify.com/CVE-2018-1121/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2018-1121
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2018-1121
- OSV: https://osv.dev/vulnerability/CVE-2018-1121

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From sbomify Insights: https://insights.sbomify.com/CVE-2018-1121/
Summaries are generated and may contain mistakes; the official description above is the record.