# CVE-2020-25040: Insecure permissions on build temporary rootfs in Singularity

> Insecure permissions on temporary directories in Singularity allow local attackers to modify container build operations, potentially leading to privilege escalation.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/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:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Sep 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-jv9c-w74q-6762, UBUNTU-CVE-2020-25040

## What is CVE-2020-25040?

CVE-2020-25040 is a high-severity vulnerability in Opensuse Leap, published on 16 Sep 2020. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

Sylabs Singularity through 3.6.2 has Insecure Permissions on temporary directories used in explicit and implicit container build operations, a different vulnerability than CVE-2020-25039.

Weakness: CWE-668 (Exposure of Resource to Wrong Sphere)

## Which versions are affected by CVE-2020-25040?

2 open source packages ship an affected version, including github.com/sylabs/singularity. It affects 2 products.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/sylabs/singularity` | Go | All versions | 3.6.3 |
| `github.com/sylabs/singularity` | Go | All versions | 3.6.3 |

Products: Opensuse Leap, Sylabs Singularity.

## How do I fix CVE-2020-25040?

Upgrade github.com/sylabs/singularity to 3.6.3 or later.

## Is CVE-2020-25040 being exploited?

There is no known exploitation of CVE-2020-25040 in the wild and no public exploit code.

## Other vulnerabilities in Opensuse Leap

- [CVE-2015-4902](https://insights.sbomify.com/CVE-2015-4902/): Oracle Java SE Integrity Check (medium 5.3, exploited in the wild)
- [CVE-2017-14804](https://insights.sbomify.com/CVE-2017-14804/): package builds could use directory traversal to write outside of target area (critical 9.9)
- [CVE-2019-20787](https://insights.sbomify.com/CVE-2019-20787/): Teeworlds before 0.7.4 has an integer overflow when computing a tilemap size. (critical 9.8)
- [CVE-2019-8341](https://insights.sbomify.com/CVE-2019-8341/): Code injection in n/a (critical 9.8)
- [CVE-2019-6438](https://insights.sbomify.com/CVE-2019-6438/): Other in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-25040 and fix it if it is affected.

What it is: CVE-2020-25040 is a high-severity vulnerability in Opensuse Leap, published on 16 Sep 2020. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-25040 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/sylabs/singularity (Go): affected all versions; fixed in 3.6.3
- github.com/sylabs/singularity (Go): affected all versions; fixed in 3.6.3

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-2020-25040/ (Markdown: https://insights.sbomify.com/CVE-2020-25040/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-25040
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-25040
- OSV: https://osv.dev/vulnerability/CVE-2020-25040

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-25040/
Summaries are generated and may contain mistakes; the official description above is the record.