Host memory leak via unreleased rooted references
Published Oct 7, 2025 · Updated Oct 7, 2025
Memory leaks in Wasmtime 37.0.0 and 37.0.1 C/C++ bindings allow attackers to consume host memory through anyref or externref values. The OwnedRooted refactor left wasmtime_val_unroot ineffective, failed to unroot host-function return values, and omitted C++ destructors, leaving allocations outside the store permanently rooted. Exposure requires a C/C++ embedding that uses anyref or externref; the Rust crate and embeddings that avoid both reference types are unaffected.
Summary
What happened
Memory leaks in Wasmtime 37.0.0 and 37.0.1 C/C++ bindings allow attackers to consume host memory through anyref or externref values. The OwnedRooted refactor left wasmtime_val_unroot ineffective, failed to unroot host-function return values, and omitted C++ destructors, leaving allocations outside the store permanently rooted. Exposure requires a C/C++ embedding that uses anyref or externref; the Rust crate and embeddings that avoid both reference types are unaffected.
The record
- CVE
- CVE-2025-61670
- Published
- Oct 7, 2025
- Updated
- Oct 7, 2025
- Vendor
- Bytecode Alliance
- Product
- Wasmtime
- Classifications
- CWE-772, T1499.004
- Attack vector
- adjacent
- Privileges
- authenticated
Timeline
How it unfolded
- Oct 7, 2025CVE publishedPublication date reported by the CVE source.
- Oct 7, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=>= 37.0.0, < 37.0.2
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo