Host crash via uninitialized externref drop
Published Feb 16, 2022 · Updated Apr 23, 2025
Memory corruption in Bytecode Alliance Wasmtime before 0.33.1 and Wasmtime 0.34.0 allows attackers to crash the host during module loading. The pooling instance allocator drops an uninitialized VMExternRef when initialization fails before the VMContext and externref globals are ready. Exploitation requires reference types, the nondefault pooling allocator, a qualifying module, and an allocation or resource-limiter failure; controlled memory can theoretically enable code execution.
Summary
What happened
Memory corruption in Bytecode Alliance Wasmtime before 0.33.1 and Wasmtime 0.34.0 allows attackers to crash the host during module loading. The pooling instance allocator drops an uninitialized VMExternRef when initialization fails before the VMContext and externref globals are ready. Exploitation requires reference types, the nondefault pooling allocator, a qualifying module, and an allocation or resource-limiter failure; controlled memory can theoretically enable code execution.
The record
- CVE
- CVE-2022-23636
- Published
- Feb 16, 2022
- Updated
- Apr 23, 2025
- Vendor
- Bytecode Alliance
- Product
- Wasmtime
- Classifications
- CWE-824, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 16, 2022CVE publishedPublication date reported by the CVE source.
- Apr 23, 2025Record 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=< 0.33.0
- Affected versionversion== 0.34.0
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
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Technologies
Your stack
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Your stack
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