Vulnerability in Bytecodealliance Wasm-Micro-Runtime
CVE-2025-43853
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.
EPSS: 0.002 (15.3th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N.
Affected products
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Third Party Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
Frequently asked questions
- What is CVE-2025-43853?
- CVE-2025-43853 is a medium-severity vulnerability in Bytecodealliance Wasm-Micro-Runtime, classified under UNIX Symbolic Link (Symlink) Following. CVSS score: 5.5/10. Published 2025-05-15.
- How severe is CVE-2025-43853?
- Medium severity. CVSS v3 base score is 5.5 out of 10.
- Is CVE-2025-43853 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.