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Heap-based Buffer OverflowWeakness · CWE-122

CVE-2026-40504

CRITICAL · 9.8 CVSS v3.1 Published 2026-04-16
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
100/100
Remediation priority · Urgent
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
Creolabs Gravity before 0.9.6 contains a heap buffer overflow vulnerability in the gravity_vm_exec function that allows attackers to write out-of-bounds memory by crafting scripts with many string literals at global scope. Attackers can exploit insufficient bounds checking in gravity_fiber_reassign() to corrupt heap metadata and achieve arbitrary code execution in applications that evaluate untrusted scripts.

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

Creolabs Gravity before version 0.9.6 contains a heap buffer overflow vulnerability in gravity_vm_exec caused by insufficient bounds checking in gravity_fiber_reassign(). Attackers can exploit this by crafting scripts with many string literals at global scope, corrupting heap metadata to achieve arbitrary code execution in applications that evaluate untrusted scripts.

MitigationUpgrade to Gravity version 0.9.6 or later. If immediate upgrading is not feasible, avoid evaluating untrusted scripts and implement input validation or sandboxing as a temporary mitigation.

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 checks

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

  1. Identify Gravity installation and version
    Run `gravity -v` or check the binary/version info for Creolabs Gravity installed in your environment
    Affected if The installed version is below 0.9.6 (e.g., 0.9.5, 0.9.4, etc.)
  2. Confirm application evaluates untrusted scripts
    Review your application code or configuration to determine if it accepts and executes scripts from untrusted sources (e.g., user-provided scripts, external API scripts, script files from unknown origins)
    Affected if Your application evaluates scripts from untrusted or unauthenticated sources using the Gravity interpreter
  3. Check for script evaluation features
    Inspect running processes and application configurations for Gravity script execution endpoints, APIs, or file processing that handles .gravity script files from external sources
    Affected if The application exposes script evaluation functionality to untrusted inputs without sandboxing
  4. Identify heap corruption indicators
    Monitor application logs and system diagnostics for heap-related errors, memory corruption warnings, or crashes originating from gravity_vm_exec or gravity_fiber_reassign functions
    Affected if Heap buffer overflow symptoms appear in logs or crash dumps tied to Gravity's VM execution

You are affected if Creolabs Gravity version is below 0.9.6 AND your application evaluates scripts from untrusted sources, enabling crafted scripts with many string literals to trigger the heap buffer overflow in gravity_vm_exec.

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
Patch available Apply the vendor patch
Vendor patch github.com →
Interim mitigation

Upgrade to Gravity version 0.9.6 or later. If immediate upgrading is not feasible, avoid evaluating untrusted scripts and implement input validation or sandboxing as a temporary mitigation.

Recommended fix High confidence

Gravity 0.9.6

  1. Identify the current Gravity version in use by running `gravity -v` or checking the version in your build system.
  2. Download Gravity version 0.9.6 or later from the official GitHub repository: https://github.com/marcobambini/gravity
  3. If using a package manager, upgrade to the latest package that includes version 0.9.6 or later.
  4. Rebuild and recompile any applications or services that use the Gravity interpreter to ensure they link against the patched version.
  5. Verify the upgrade was successful by checking `gravity -v` shows version 0.9.6 or higher.
  6. If evaluating untrusted scripts, ensure the patched version is deployed in production environments.

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA3.0 h
15.0 hours of engineering $2,560
Get the patch applied

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,096.

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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-2026-40504 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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