# CVE-2025-43853: iwasm vulnerable to filesystem sandbox escape with symlink when using uvwasi feature

> Attackers can escape the filesystem sandbox via symlinks to read or create files on the host system when using the uvwasi feature on Windows.

- **Severity:** High 7.0 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 May 2025
- **Updated:** 15 May 2025
- **Also known as:** GHSA-8fc8-4g25-c8m7

## What is CVE-2025-43853?

CVE-2025-43853 is a high-severity path traversal vulnerability in bytecodealliance wasm-micro-runtime, published on 15 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

The WebAssembly Micro Runtime's (WAMR) iwasm package is the executable binary built with WAMR VMcore which supports WebAssembly System Interface (WASI) and command line interface. Anyone running WAMR up to and including version 2.2.0 or WAMR built with libc-uvwasi on Windows is affected by a symlink following vulnerability. On WAMR running in Windows, creating a symlink pointing outside of the preopened directory and subsequently opening it with create flag will create a file on host outside of the sandbox. If the symlink points to an existing host file, it's also possible to open it and read its content. Version 2.3.0 fixes the issue.

Weakness: CWE-61 (UNIX Symbolic Link (Symlink) Following)

## Which versions are affected by CVE-2025-43853?

It affects 1 product.


Products: Bytecodealliance Webassembly Micro Runtime.

## How do I fix CVE-2025-43853?

No fix has been published for CVE-2025-43853 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-43853 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-43853 exists.

## Other vulnerabilities in bytecodealliance wasm-micro-runtime

- [CVE-2024-25431](https://insights.sbomify.com/CVE-2024-25431/): Memory corruption in n/a (high 8.8)
- [CVE-2024-27532](https://insights.sbomify.com/CVE-2024-27532/): Null dereference in n/a (high 7.5)
- [CVE-2024-34251](https://insights.sbomify.com/CVE-2024-34251/): Memory corruption in n/a (high 7.5)
- [CVE-2023-48105](https://insights.sbomify.com/CVE-2023-48105/): Memory corruption in n/a (high 7.5)
- [CVE-2025-54126](https://insights.sbomify.com/CVE-2025-54126/): WebAssembly Micro Runtime's `--addr-pool` option allows all IPv4 addresses when subnet mask is not specified (medium 6.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-43853 and fix it if it is affected.

What it is: CVE-2025-43853 is a high-severity path traversal vulnerability in bytecodealliance wasm-micro-runtime, published on 15 May 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-43853 exists.

Affected product: bytecodealliance wasm-micro-runtime. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-43853/ (Markdown: https://insights.sbomify.com/CVE-2025-43853/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-43853
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-43853
- OSV: https://osv.dev/vulnerability/CVE-2025-43853

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-43853/
Summaries are generated and may contain mistakes; the official description above is the record.