CVE-2026-1774
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 · uneditedCASL Ability, versions 2.4.0 through 6.7.4, contains a prototype pollution vulnerability.
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 · high confidenceCASL Ability versions 2.4.0 through 6.7.4 contain a prototype pollution vulnerability. This JavaScript permissions library fails to properly sanitize user input when merging objects, allowing attackers to inject properties into Object.prototype. This can lead to denial of service, privilege escalation, or remote code execution depending on how the application uses the polluted prototype properties.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS 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 CASL Ability installed versionRun 'npm list @casl/ability' or inspect package.json to see the installed version of @casl/abilityAffected if Installed version is 2.4.0 through 6.7.4 (vulnerable range)
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Identify code paths using CASL merge operationsSearch your codebase for calls to CASL methods that merge objects, such as 'AbilityBuilder', 'createAbility', or any custom code that passes user input to CASL's define() or with() methodsAffected if User-controlled input flows into CASL's object merging functionality without sanitization
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Audit Ability definition codeReview all files where Ability is defined or updated. Look for patterns where request parameters, API body data, or external data is directly assigned to ability rules without validationAffected if Untrusted input is directly used in ability definition construction
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Verify prototype pollution defensesInspect application startup code to see if Object.prototype has been frozen via Object.freeze(Object.prototype) as a temporary mitigationAffected if Object.prototype is NOT frozen and vulnerable CASL version is in use
You are affected if CASL Ability version 2.4.0-6.7.4 is installed AND your application passes user-supplied data to CASL's ability definition or merge operations without sanitization.
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.
From vendor dataUpgrade CASL Ability to the latest version (6.7.5 or later) which contains the security fix. If immediate upgrading is not possible, audit all code paths that pass user-controlled input to CASL's ability definitions and consider freezing Object.prototype using Object.freeze(Object.prototype) as a temporary mitigation.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-1774 — 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-2026-1774 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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- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
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