Filesystem Datetime Overflow Vulnerability in Wasmtime-WASI
Summary
RUSTSEC-2026-0314: Guest can panic host through filesystem datetime overflow. Affects wasmtime-wasi across 3 version ranges.
>= 0.0.0-0, < 36.0.16
>= 37.0.0, < 48.0.3
>= 49.0.0, < 49.0.1
Fixed in 36.0.16, 48.0.3 or 49.0.1, depending on the release line you run. How to fix ↓
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Background
Wasmtime is a standalone JIT-style runtime for WebAssembly, designed to run WebAssembly modules efficiently and securely. The wasmtime-wasi package provides an interface for running WebAssembly modules that require access to the WebAssembly System Interface (WASI). This package is crucial for developers looking to integrate WebAssembly into their applications, allowing for enhanced performance and portability. However, it has been found to have a vulnerability that can lead to a host panic through filesystem datetime overflow, posing a significant risk to applications utilizing this package.
Vulnerability Detail
The vulnerability identified as RUSTSEC-2026-0314 allows a guest to cause a panic in the host system through an overflow in the filesystem datetime handling. This issue arises from improper validation of datetime inputs, which can lead to unexpected behavior and crashes in the host environment. The potential ramifications include service disruptions and security breaches, as attackers could exploit this vulnerability to destabilize applications relying on the wasmtime-wasi package. The vulnerability has been assigned a CVSS score of 6.2, indicating a moderate severity level.
How To Fix
Latest published version: 50.0.0 as of 22 Oct 2026
Upgrading to it may include breaking changes; the versions below are the minimum fixed release for this vulnerability.
If you can't move to the latest
The minimum fixed version depends on the release line you run.
-
>= 0.0.0-0, < 36.0.1636.0.16 -
>= 37.0.0, < 48.0.348.0.3 -
>= 49.0.0, < 49.0.149.0.1
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Workaround
If immediate updating is not feasible, consider implementing input validation on datetime values before they are processed by the wasmtime-wasi package. This can help mitigate the risk of overflow by ensuring that only valid datetime inputs are accepted.
Conclusion
The filesystem datetime overflow vulnerability in the wasmtime-wasi package poses a significant risk to applications using this runtime. It is crucial for developers to update to the latest patched versions to ensure the security and stability of their applications. Additionally, implementing input validation can serve as a temporary measure to mitigate potential risks.
See every vulnerability recorded for wasmtime-wasi →
FAQ
The vulnerability allows a guest to cause a panic in the host system through an overflow in filesystem datetime handling.
The affected versions include all versions prior to 36.0.16, 48.0.3, and 49.0.1.
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The CVSS score of this vulnerability is 6.2, indicating a moderate severity level.
Implement input validation on datetime values to mitigate the risk of overflow until you can update to a patched version.
References
Related vulnerabilities
Recent vulnerabilities recorded for wasmtime-wasi.
