CVE-2021-33622
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedSylabs Singularity 3.5.x and 3.6.x, and SingularityPRO before 3.5-8, has an Incorrect Check of a Function's Return Value.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · moderate confidenceA vulnerability in Sylabs Singularity container runtime versions 3.5.x, 3.6.x, and SingularityPRO before 3.5-8 involves an incorrect check of a function's return value. This could allow an attacker to bypass security controls, potentially leading to container escape or privilege escalation due to improper error handling in the container execution path.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 3.5.0, < 3.7.0< 3.5-8CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check Singularity version installedRun `singularity --version` to retrieve the installed version numberAffected if Version is 3.5.0 through 3.6.x, or version is 3.7.0 or higher (only 3.5.0 to <3.7.0 are affected per the CVE)
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Confirm SingularityPRO editionIf using SingularityPRO, check the specific version with `singularity --version` and verify it is not version 3.5-8 or laterAffected if Running SingularityPRO with version lower than 3.5-8
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Identify who can execute SingularityCheck /etc/subuid and /etc/subgid for user mappings, and review permissions on the singularity binary with `ls -la $(which singularity)`Affected if Untrusted or unprivileged users have access to run Singularity containers, enabling the exploitation path
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Review container execution permissionsInspect any Singularity definition files or container runtime policies in the environment to determine if users can execute containers without root privilegesAffected if Non-root users can execute containers, which combined with a vulnerable version creates the bypass condition
You are affected if Singularity version is 3.5.0 or higher but below 3.7.0 (or SingularityPRO below 3.5-8) AND untrusted users can execute containers in your environment.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.5-83.7.0
Upgrade Singularity to version 3.5-8 or later for SingularityPRO, or to 3.7.0+ for standard releases. If immediate patching is not possible, restrict untrusted users from running Singularity containers and enable available security mechanisms.
Singularity 3.7.0+ or SingularityPRO 3.5-8+
- Check current Singularity version by running: singularity --version
- For Singularity: Upgrade to version 3.7.0 or later
- For SingularityPRO: Upgrade to version 3.5-8 or later
- Verify the upgrade was successful by running: singularity --version
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation1.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-33622 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-33622 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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