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QuickjsApplication · Quickjs Ng

CVE-2026-0821

CRITICAL · 9.8 CVSS v3.1 Published 2026-01-10
Fix available
A fix is available. Upgrade to after 0.11.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click Patch available

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 · unedited
A vulnerability was determined in quickjs-ng quickjs up to 0.11.0. This vulnerability affects the function js_typed_array_constructor of the file quickjs.c. Executing a manipulation can lead to heap-based buffer overflow. The attack may be launched remotely. The exploit has been publicly disclosed and may be utilized. This patch is called c5d80831e51e48a83eab16ea867be87f091783c5. A patch should be applied to remediate this issue.

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 confidence

Heap-based buffer overflow vulnerability in the js_typed_array_constructor function in quickjs.c allows remote attackers to overflow heap buffers via manipulated JavaScript TypedArray operations. The vulnerability affects quickjs-ng versions up to 0.11.0.

MitigationApply patch commit c5d80831e51e48a83eab16ea867be87f091783c5 to fix the bounds checking in js_typed_array_constructor. Given the critical CVSS score (9.8) and public exploit availability, prioritize immediate testing and deployment.

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
QuickjsApplication
Affected:<= 0.11.0

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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify QuickJS NG installation
    Run 'quickjs --version' or check for quickjs binary in common paths like /usr/bin/quickjs, /usr/local/bin/quickjs, or search for files named 'quickjs' or 'quickjs-ng' in the system
    Affected if QuickJS NG is present on the system
  2. Determine the QuickJS NG version
    Execute 'quickjs --version' and note the version number displayed, or check the binary's metadata
    Affected if Version is 0.11.0 or lower (any version up to and including 0.11.0)
  3. Check if untrusted JavaScript code execution is possible
    Review application architecture to determine if QuickJS processes JavaScript from untrusted sources such as user input, network requests, or external files
    Affected if QuickJS processes or could process untrusted JavaScript code
  4. Determine if TypedArray operations are accessible
    Audit the JavaScript code being executed to check if it includes TypedArray operations (such as new Uint8Array, new Int16Array, new Float32Array, etc.) or if user-controlled scripts can invoke these constructors
    Affected if The QuickJS interpreter executes or may execute JavaScript containing TypedArray constructor calls
  5. Check for network exposure or remote input handling
    Examine whether QuickJS is embedded in a networked application, API, or service that accepts remote JavaScript input, or if it runs in a sandboxed environment with user-provided scripts
    Affected if QuickJS is exposed to remote or untrusted input sources

If QuickJS NG version 0.11.0 or lower is installed and it processes untrusted JavaScript code containing TypedArray operations, the environment is affected by CVE-2026-0821.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to a release after 0.11.0
Vendor patch github.com →
Interim mitigation

Apply patch commit c5d80831e51e48a83eab16ea867be87f091783c5 to fix the bounds checking in js_typed_array_constructor. Given the critical CVSS score (9.8) and public exploit availability, prioritize immediate testing and deployment.

Recommended fix Moderate confidence

Version 0.12.0 or later (any release containing commit c5d80831e51e48a83eab16ea867be87f091783c5)

  1. 1. Identify the current quickjs-ng version in use (e.g., run `quickjs --version` or check package.json/dependencies)
  2. 2. Navigate to the quickjs-ng GitHub repository at https://github.com/quickjs-ng/quickjs
  3. 3. Check the release notes or tags to find a version released after commit c5d80831e51e48a83eab16ea867be87f091783c5
  4. 4. Download or update to the nearest subsequent release version (likely 0.12.0 or later)
  5. 5. Rebuild any applications or libraries that link against quickjs
  6. 6. Verify the upgrade by running `quickjs --version` to confirm the new version is installed
  7. 7. Retest the application to ensure functionality is preserved
Caveat Verify compatibility with any custom quickjs extensions or bindings used in your application, as minor version increments in quickjs-ng may include API changes

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Quickjs Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing12.0 h
  • Review / QA4.0 h
25.0 hours of engineering $4,200
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-0821 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data