Wasmtime before 36.0.18, 37.0.0 before 48.0.6, and 49.0.0 before 49.0.3 Sandbox Escape via Symlink Rename

Summary

wasmtime-wasi in Wasmtime before 36.0.18, 37.0.0 before 48.0.6, and 49.0.0 before 49.0.3 re-appends a trailing slash to rename source paths, causing renameat on macOS and FreeBSD hosts to follow directory symlinks. A guest with sandbox write access can rename a relative symlink such as "up/" to move host directories into its sandbox and read or write them.

Remediation

1. Inventory every bytecodealliance wasmtime deployment, including staging.
2. Upgrade bytecodealliance wasmtime to the fixed version for your release line, listed under Affected versions.
3. Confirm the running version after the upgrade.

References

• Advisoryhttps://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-m9f7-9w4p-gv38
• Advisoryhttps://www.vulncheck.com/advisories/wasmtime-before-36.0.18-37.0.0-before-48.0.6-and-49.0.0-before-49.0.3-sandbox-escape-via-symlink-rename