Security readout for executives and security teams
Plain-English summary
Affected Singularity versions may run a container from the wrong remote library. A user intending to run a trusted internal container could instead execute a same-named container from Sylabs’ default cloud endpoint.
Executive priority
Prioritize remediation for research, HPC, or CI environments that execute library:// containers from non-default libraries. Business risk is unwanted code execution through container source confusion, not broad unauthenticated compromise.
Technical view
In Singularity 3.7.2 and 3.7.3, run, shell, and exec against library:// URIs ignore the configured remote endpoint and use cloud.sylabs.io. Pull and push respect configuration. The issue is fixed in 3.7.4.
Likely exposure
Exposure is limited to environments running Singularity 3.7.2 or 3.7.3 that execute library:// containers with run, shell, or exec while relying on a non-default remote endpoint.
Exploitation context
The source describes a malicious container with an identical URI on the default endpoint. User interaction is required. The bundle does not indicate active exploitation, and KEV status is false.
Researcher notes
The vulnerable behavior is command-specific: run, shell, and exec are affected; pull and push are not. The attack depends on URI collision and user execution of a library:// reference.
Mitigation direction
- Upgrade Singularity to version 3.7.4 or later.
- Use only the default remote endpoint until upgraded.
- Configure execution control lists to allow only containers signed by trusted keys.
- Review vendor guidance before choosing compensating controls.
Validation and detection
- Inventory Singularity versions and flag 3.7.2 or 3.7.3 installations.
- Identify workflows using run, shell, or exec with library:// URIs.
- Check whether affected hosts use a non-default remote endpoint.
- Confirm upgraded hosts are on Singularity 3.7.4 or later.
- Verify execution control lists enforce trusted signing keys where used.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-20: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-923: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupContainer behavior lookup
The affected technology mentions containers, so container-specific ATT&CK technique review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-32635 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L2.83.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/sylabs/singularity/security/advisories/GHSA-5mv9-q7fq-9394CVE reference · x_refsource_CONFIRM
- https://github.com/sylabs/singularity/releases/tag/v3.7.4CVE reference · x_refsource_MISC
- GLSA-202107-50CVE reference · vendor-advisory, x_refsource_GENTOO
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Improper Restriction of Communication Channel to Intended Endpoints
Improper Restriction of Communication Channel to Intended Endpoints represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.