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

State: Published
Severity: 8.8 High
Published: Oct 28, 2026
Updated: Oct 28, 2026
Reserved: Oct 28, 2026

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.

Scores

CVSS	Score	Vector	Source
4.0	8.8 High	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	VulnCheck
3.1	7.9 High	CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:L	VulnCheck

Weaknesses

CWE-61 UNIX Symbolic Link (Symlink) Following

Affected Products

Product	Versions
wasmtimebytecodealliance	before 36.0.18Affected 36.0.18Not affected 37.0.0 to before 48.0.6Affected 48.0.6Not affected 49.0.0 to before 49.0.3Affected 49.0.3Not affected

References

GitHub Security Advisory (GHSA-m9f7-9w4p-gv38)vendor-advisory
VulnCheck Advisory: Wasmtime before 36.0.18, 37.0.0 before 48.0.6, and 49.0.0 before 49.0.3 Sandbox Escape via Symlink Renamethird-party-advisory

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