Vulnerability in Bytecodealliance Wasmtime
CVE-2026-118688
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.9 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/bytecodealliance/wasmtime/security/advisories/GHSA-m9f7-9w4p-gv38 (vendor-advisory)
- www.vulncheck.com/advisories/wasmtime-before-36.0.18-37.0.0-before-48.0.6-and-4… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-118688?
- CVE-2026-118688 is a high-severity vulnerability in Bytecodealliance Wasmtime, classified under UNIX Symbolic Link (Symlink) Following. CVSS score: 7.9/10. Published 2026-10-28.
- How severe is CVE-2026-118688?
- High severity. CVSS v3 base score is 7.9 out of 10.