---
id: CVE-2021-32635
aliases:
  - GHSA-5mv9-q7fq-9394
title: >-
  Action Commands (run/shell/exec) Against Library URIs Ignore Configured Remote
  Endpoint
summary: >-
  Action Commands (run/shell/exec) Against Library URIs Ignore Configured Remote
  Endpoint
severity: medium
cvss: 6.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L'
vendor: sylabs
product: github.com/sylabs/singularity
ecosystem: go
affected:
  - 'github.com/sylabs/singularity >= 3.7.2, < 3.7.4'
patched:
  - github.com/sylabs/singularity 3.7.4
published: '2021-06-01'
updated: '2026-07-08'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-5mv9-q7fq-9394'
references:
  - url: >-
      https://github.com/hpcng/singularity/security/advisories/GHSA-jq42-hfch-42f3
  - url: >-
      https://github.com/sylabs/singularity/security/advisories/GHSA-5mv9-q7fq-9394
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2021-32635'
  - url: >-
      https://github.com/sylabs/singularity/commit/d52ae9d13979733c5e987a566fae59ed6f1bf796
  - url: 'https://github.com/sylabs/singularity'
  - url: 'https://github.com/sylabs/singularity/releases/tag/v3.7.4'
  - url: 'https://security.gentoo.org/glsa/202107-50'
tags:
  - osv
  - go
epss: 0.01415
epssPercentile: 0.71573
ingestedAt: '2026-07-09T18:56:35.938Z'
---

## Overview

### Impact

Due to incorrect use of a default URL, `singularity` action commands (`run`/`shell`/`exec`) specifying a container using a `library://` URI will always attempt to retrieve the container from the default remote endpoint (`cloud.sylabs.io`) rather than the configured remote endpoint.

An attacker may be able to push a malicious container to the default remote endpoint with a URI that is identical to the URI used by a victim with a non-default remote endpoint, thus executing the malicious container.

Only action commands (`run`/`shell`/`exec`) against `library://` URIs are affected. Other commands such as `pull` / `push` respect the configured remote endpoint.

### Patches

All users should upgrade to Singularity 3.7.4 or later.

A patch was applied at: https://github.com/sylabs/singularity/commit/d52ae9d13979733c5e987a566fae59ed6f1bf796

### Workarounds

Users who only interact with the default remote endpoint are not affected.

Installations with an execution control list configured to restrict execution to containers signed with specific secure keys are not affected.

### For more information

General questions about the impact of the advisory can be asked in the:

- [SingularityCE Slack Channel](https://singularityce.slack.com)
- [SingularityCE Mailing List](https://groups.google.com/g/singularity-ce)

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 >= 3.7.2, < 3.7.4`

## Remediation

Upgrade to a patched release:

- `github.com/sylabs/singularity 3.7.4`