Buffer overflow in Bytecodealliance Wasmtime
CVE-2026-115393
Wasmtime before 24.0.12, 25.0.0 before 36.0.13, 37.0.0 before 46.0.2, and 47.0.0 before 47.0.3 contains a type confusion vulnerability because several Store APIs fail to validate that objects belong to the Store's Engine. Embedders mixing objects between Engines via Instance::new, StructRefPre::new, or Tag::new can trigger trampoline signature mismatches causing out-of-bounds stack writes, GC heap corruption, or panics.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 3.8 (Low). Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:L/I:L/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-hgjw-h833-99q9 (vendor-advisory)
- www.vulncheck.com/advisories/wasmtime-before-24.0.12-25.0.0-before-36.0.13-37.0… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-115393?
- CVE-2026-115393 is a low-severity vulnerability in Bytecodealliance Wasmtime, classified under Out-of-bounds Write. CVSS score: 3.8/10. Published 2026-10-22.
- How severe is CVE-2026-115393?
- Low severity. CVSS v3 base score is 3.8 out of 10.