---
id: CVE-2020-25040
aliases:
  - GHSA-jv9c-w74q-6762
title: Insecure permissions on build temporary rootfs in Singularity
summary: Insecure permissions on build temporary rootfs in Singularity
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
vendor: sylabs
product: github.com/sylabs/singularity
ecosystem: go
affected:
  - github.com/sylabs/singularity < 3.6.3
patched:
  - github.com/sylabs/singularity 3.6.3
published: '2021-05-24'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-jv9c-w74q-6762'
references:
  - url: >-
      https://github.com/hpcng/singularity/security/advisories/GHSA-jv9c-w74q-6762
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2020-25040'
  - url: 'https://medium.com/sylabs'
  - url: 'http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00070.html'
  - url: 'http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00088.html'
tags:
  - osv
  - go
epss: 0.0204
epssPercentile: 0.80273
ingestedAt: '2026-07-09T18:56:36.595Z'
---

## Overview

### Impact

Insecure permissions on temporary directories used in explicit and implicit container build operations.

When a Singularity command that results in a container build operation is executed, it is possible for a user with access to the system to read the contents of the image during the build. Additionally, if the image contains a world-writable file or directory, it is possible for a user to inject arbitrary content into the running build, which in certain circumstances may enable arbitrary code execution during the build and/or when the built container is run.

### Patches

This issue is addressed in Singularity 3.6.3.

All users are advised to upgrade to 3.6.3.

### Workarounds

The issue is mitigated if `TMPDIR` is set to a location that is only accessible to the user, as any subdirectories directly under `TMPDIR` cannot then be accessed by others. However, this is difficult to enforce so it is not recommended to rely on this as a mitigation.

### For more information

General questions about the impact of the advisory / changes made in the 3.6.0 release can be asked in the:

* [Singularity Slack Channel](https://bit.ly/2m0g3lX)
* [Singularity Mailing List](https://groups.google.com/a/lbl.gov/forum/??sdf%7Csort:date#!forum/singularity)

Any sensitive security concerns should be directed to: security@sylabs.io

See our Security Policy here: https://sylabs.io/security-policy

## Affected packages

- `github.com/sylabs/singularity < 3.6.3`

## Remediation

Upgrade to a patched release:

- `github.com/sylabs/singularity 3.6.3`