CVE-2025-43853: iwasm vulnerable to filesystem sandbox escape with symlink when using uvwasi feature
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.
Classification
CVE ID: CVE-2025-43853
CVSS Base Severity: HIGH
CVSS Base Score: 7.0
CVSS Vector: 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
Problem Types
CWE-61: UNIX Symbolic Link (Symlink) FollowingAffected Products
Vendor: bytecodealliance
Product: wasm-micro-runtime
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.02% (probability of being exploited)
EPSS Percentile: 3.24% (scored less or equal to compared to others)
EPSS Date: 2025-06-13 (when was this score calculated)
References
https://nvd.nist.gov/vuln/detail/CVE-2025-43853https://github.com/bytecodealliance/wasm-micro-runtime/security/advisories/GHSA-8fc8-4g25-c8m7
https://github.com/bytecodealliance/wasm-micro-runtime/commit/28702edaf739cdeee54e81efe5868bf00724c33c