# CVE-2020-15702: TOCTOU in apport

> A local attacker can exploit a TOCTOU race condition in apport to escalate privileges and execute arbitrary code via PID recycling.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/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:** 6 Aug 2020
- **Updated:** 3 Nov 2025
- **Also known as:** GHSA-r8j7-rc3f-2wqq, UBUNTU-CVE-2020-15702

## What is CVE-2020-15702?

CVE-2020-15702 is a high-severity vulnerability in Canonical Ubuntu Linux, published on 6 Aug 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

TOCTOU Race Condition vulnerability in apport allows a local attacker to escalate privileges and execute arbitrary code. An attacker may exit the crashed process and exploit PID recycling to spawn a root process with the same PID as the crashed process, which can then be used to escalate privileges. Fixed in 2.20.1-0ubuntu2.24, 2.20.9 versions prior to 2.20.9-0ubuntu7.16 and 2.20.11 versions prior to 2.20.11-0ubuntu27.6. Was ZDI-CAN-11234.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2020-15702?

It affects 2 products.


Products: Canonical Apport, Canonical Ubuntu Linux.

## How do I fix CVE-2020-15702?

Apply the vendor's patch.

## Is CVE-2020-15702 being exploited?

There is no known exploitation of CVE-2020-15702 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2021-25682](https://insights.sbomify.com/CVE-2021-25682/): apport improperly parses /proc/pid/status (high 8.8)
- [CVE-2021-25683](https://insights.sbomify.com/CVE-2021-25683/): apport improperly parses /proc/pid/stat (high 8.8)
- [CVE-2021-25684](https://insights.sbomify.com/CVE-2021-25684/): apport can be stalled by reading a FIFO (high 8.8)
- [CVE-2021-3899](https://insights.sbomify.com/CVE-2021-3899/): Race condition in Apport (high 7.8)
- [CVE-2022-1242](https://insights.sbomify.com/CVE-2022-1242/): Other in Apport (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-15702 and fix it if it is affected.

What it is: CVE-2020-15702 is a high-severity vulnerability in Canonical Ubuntu Linux, published on 6 Aug 2020. 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-2020-15702 in the wild and no public exploit code.

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-2020-15702/ (Markdown: https://insights.sbomify.com/CVE-2020-15702/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-15702
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-15702
- OSV: https://osv.dev/vulnerability/CVE-2020-15702

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-15702/
Summaries are generated and may contain mistakes; the official description above is the record.