Sylabs · Singularity · CVE-2021-32635
**Name of the Vulnerable Software and Affected Versions**
Singularity versions 3.7.2 through 3.7.3
**Description**
The issue is related to the incorrect use of a default URL in Singularity, causing `singularity` action commands (`run`/`shell`/`exec`) to retrieve containers from the default remote endpoint (`cloud.sylabs.io`) instead of the configured remote endpoint when using a `library://` URI. This could allow an attacker to push a malicious container to the default remote endpoint, potentially executing it on a victim's system. Only action commands against `library://` URIs are affected, while other commands like `pull` and `push` respect the configured remote endpoint.
**Recommendations**
For Singularity versions 3.7.2 and 3.7.3, upgrade to Singularity version 3.7.4 or later to resolve the issue.
As a temporary workaround, users can only interact with the default remote endpoint.
Alternatively, installations can configure an execution control list to restrict execution to containers signed with specific secure keys.