Vulnerability · Published May 28, 2021 · Assigned by GitHub_M
CVE-2021-32635Action Commands (run/shell/exec) Against Library URIs Ignore Configured Remote Endpoint
Medium 6.3
In plain English
A medium-severity improper input validation in singularity from sylabs. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.4% (higher than 73% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Singularity is an open source container platform. In verions 3.7.2 and 3.7.3, Dde 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. The vulnerability is patched in Singularity version 3.7.4. Two possible workarounds exist: Users can only interact with the default remote endpoint, or an installation can have an execution control list configured to restrict execution to containers signed with specific secure keys.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | singularity | 3.7.4-r0 | ALPINE-CVE-2021-32635 |
| Alpine:v3.21 | singularity | 3.7.4-r0 | ALPINE-CVE-2021-32635 |
| Alpine:v3.22 | singularity | 3.7.4-r0 | ALPINE-CVE-2021-32635 |
| Alpine:v3.23 | singularity | 3.7.4-r0 | ALPINE-CVE-2021-32635 |
| Alpine:v3.24 | singularity | 3.7.4-r0 | ALPINE-CVE-2021-32635 |
| Go | github.com/sylabs/singularity | 3.7.4 | GHSA-5mv9-q7fq-9394 |
| Ubuntu:25.10 | singularity-container | no fix listed | UBUNTU-CVE-2021-32635 |
| Ubuntu:26.04:LTS | singularity-container | no fix listed | UBUNTU-CVE-2021-32635 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| sylabs | singularity | >= 3.7.2, <= 3.7.3 |
Weakness: CWE-923, CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
References
- https://github.com/sylabs/singularity/security/advisories/GHSA-5mv9-q7fq-9394 x_refsource_CONFIRM
- https://github.com/sylabs/singularity/releases/tag/v3.7.4 x_refsource_MISC
- GLSA-202107-50 vendor-advisory, x_refsource_GENTOO