# CVE-2026-40504: Creolabs Gravity < 0.9.6 Heap Buffer Overflow via gravity_vm_exec

> Attackers can achieve arbitrary code execution by crafting scripts with many string literals, exploiting a heap buffer overflow in the Gravity VM.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 16 Apr 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-3r49-76f3-pf2m

## What is CVE-2026-40504?

CVE-2026-40504 is a critical memory corruption vulnerability in marcobambini gravity, published on 16 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2026-40504?


## How do I fix CVE-2026-40504?

No fix has been published for CVE-2026-40504 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-40504 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40504 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-40504 and fix it if it is affected.

What it is: CVE-2026-40504 is a critical memory corruption vulnerability in marcobambini gravity, published on 16 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-40504 exists.

Affected product: marcobambini gravity. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-40504/ (Markdown: https://insights.sbomify.com/CVE-2026-40504/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-40504
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-40504
- OSV: https://osv.dev/vulnerability/CVE-2026-40504

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-40504/
Summaries are generated and may contain mistakes; the official description above is the record.