Vulnerability · Published Oct 22, 2026 · Assigned by VulnCheck

CVE-2026-115384Wasmtime 39.0.0 before 48.0.4 and 49.0.0 before 49.0.2 Stack Buffer Overflow

Critical 9.9

In plain English

A critical-severity improper input validation in wasmtime from bytecodealliance. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 24% of all known vulnerabilities).

Severity (CVSS 3.1)9.9Critical

Exploit odds (30 days)0.3%top 75.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

Wasmtime 39.0.0 before 48.0.4 and 49.0.0 before 49.0.2 contains a stack buffer overflow vulnerability that allows malicious guests to write ~16KB to the native stack via unvalidated async callback result types. Attackers can supply components with mistyped component-model-async callback functions to overwrite return addresses, crashing the host or escaping the sandbox.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Ubuntu:26.10	rust-wasmtime	no fix listed	UBUNTU-CVE-2026-115384

Affected products (as reported)

Vendor	Product	Versions
bytecodealliance	wasmtime	39.0.0 – before 48.0.449.0.0 – before 49.0.2

Weakness: CWE-20 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

References

GitHub Security Advisory (GHSA-32h6-97mm-8q3c) vendor-advisory
VulnCheck Advisory: Wasmtime 39.0.0 before 48.0.4 and 49.0.0 before 49.0.2 Stack Buffer Overflow third-party-advisory