CVE-2026-34983: CWE-416: Use After Free in bytecodealliance wasmtime
CVE-2026-34983 is a use-after-free vulnerability in the wasmtime runtime for WebAssembly, specifically affecting version 43. 0. 0. The issue arises when cloning a wasmtime::Linker, dropping the original instance, and then using the cloned instance, which leads to unsound behavior and memory safety violations. This bug cannot be triggered by guest WebAssembly programs but requires a specific sequence of host embedder API calls. The vulnerability is fixed in version 43. 0. 1. The CVSS score is low, reflecting limited impact and exploitability conditions.
AI Analysis
Technical Summary
Wasmtime 43.0.0 contains a use-after-free vulnerability (CWE-416) triggered by cloning a wasmtime::Linker, dropping the original linker, and then using the cloned linker instance. This sequence causes unsound memory usage leading to potential memory corruption. The vulnerability is not exploitable by guest Wasm programs but only through a specific sequence of host API calls. The issue is resolved in wasmtime version 43.0.1.
Potential Impact
The vulnerability can lead to use-after-free memory corruption in the host environment using wasmtime 43.0.0. Since it requires a specific sequence of host API calls and cannot be triggered by guest Wasm programs, the risk is limited. There are no known exploits in the wild. The CVSS score of 1 and low severity rating reflect the low likelihood and impact of exploitation.
Mitigation Recommendations
Upgrade wasmtime to version 43.0.1 or later, where this use-after-free vulnerability is fixed. Since the vulnerability is fixed in 43.0.1, applying this official patch fully mitigates the issue. No additional mitigations are indicated.
CVE-2026-34983: CWE-416: Use After Free in bytecodealliance wasmtime
Description
CVE-2026-34983 is a use-after-free vulnerability in the wasmtime runtime for WebAssembly, specifically affecting version 43. 0. 0. The issue arises when cloning a wasmtime::Linker, dropping the original instance, and then using the cloned instance, which leads to unsound behavior and memory safety violations. This bug cannot be triggered by guest WebAssembly programs but requires a specific sequence of host embedder API calls. The vulnerability is fixed in version 43. 0. 1. The CVSS score is low, reflecting limited impact and exploitability conditions.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Wasmtime 43.0.0 contains a use-after-free vulnerability (CWE-416) triggered by cloning a wasmtime::Linker, dropping the original linker, and then using the cloned linker instance. This sequence causes unsound memory usage leading to potential memory corruption. The vulnerability is not exploitable by guest Wasm programs but only through a specific sequence of host API calls. The issue is resolved in wasmtime version 43.0.1.
Potential Impact
The vulnerability can lead to use-after-free memory corruption in the host environment using wasmtime 43.0.0. Since it requires a specific sequence of host API calls and cannot be triggered by guest Wasm programs, the risk is limited. There are no known exploits in the wild. The CVSS score of 1 and low severity rating reflect the low likelihood and impact of exploitation.
Mitigation Recommendations
Upgrade wasmtime to version 43.0.1 or later, where this use-after-free vulnerability is fixed. Since the vulnerability is fixed in 43.0.1, applying this official patch fully mitigates the issue. No additional mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-03-31T19:38:31.617Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69d7f88c1cc7ad14da0c1703
Added to database: 4/9/2026, 7:05:48 PM
Last enriched: 4/9/2026, 7:21:45 PM
Last updated: 4/9/2026, 9:32:49 PM
Views: 3
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