Arbitrary code execution via fiber stack misallocation
Published Apr 16, 2026 · Updated Apr 16, 2026
Heap buffer overflow in Marco Bambini Gravity before 0.9.6 allows attackers to execute arbitrary code through a crafted script. During module initialization, gravity_fiber_reassign() permits a large register window to move stacktop beyond the allocated fiber stack, so gravity_vm_exec writes subsequent values out of bounds. Exploitation requires an application to evaluate attacker-controlled Gravity code; the supplied proof of concept demonstrates a crash, while the CNA reports arbitrary code execution.
Summary
What happened
Heap buffer overflow in Marco Bambini Gravity before 0.9.6 allows attackers to execute arbitrary code through a crafted script. During module initialization, gravity_fiber_reassign() permits a large register window to move stacktop beyond the allocated fiber stack, so gravity_vm_exec writes subsequent values out of bounds. Exploitation requires an application to evaluate attacker-controlled Gravity code; the supplied proof of concept demonstrates a crash, while the CNA reports arbitrary code execution.
The record
- CVE
- CVE-2026-40504
- Published
- Apr 16, 2026
- Updated
- Apr 16, 2026
- Vendor
- Marco Bambini
- Product
- Gravity
- Classifications
- CWE-122, T1203
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Apr 16, 2026CVE publishedPublication date reported by the CVE source.
- Apr 16, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <0.9.6
- Affected versionversion=0 <18b9195598d9b944376754c6d1ad76e38a4adca1
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- Gravity issue 437 proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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