CVE-2026-126409

EUVD-2026-125034

13.11.2026, 10:17

Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains a cross-engine type confusion vulnerability because StructType::with_finality_and_supertype does not validate that the supplied supertype belongs to the same Engine. Embedders using multiple engines that create a GC struct type with another engine's supertype can trigger runtime panics or GC heap corruption, causing denial of service; guest WebAssembly cannot trigger it.

Type Confusion

Provider	Type	Base Score	Atk. Vector	Atk. Complexity	Priv. Required	Vector
VulnCheck	CNA	2 LOW	NETWORK	HIGH	HIGH	CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L

Base Score

CVSS 3.x

EPSS Score

Percentile: 19.52%

Early Detection

Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).

Vendor	Product	Version	Source
bytecodealliance	wasmtime	47.0.0 ≤ 𝑥 < 48.0.8	CNA
bytecodealliance	wasmtime	49.0.0 ≤ 𝑥 < 49.0.5	CNA
bytecodealliance	wasmtime	50.0.0 ≤ 𝑥 < 50.0.1	CNA

Ubuntu Releases

Ubuntu Product

Codename

rust-wasmtime

jammy	dne
noble	needs-triage
resolute	needs-triage
stonking	needs-triage

Common Weakness Enumeration

CWE-843 - Access of Resource Using Incompatible Type ('Type Confusion')
The program allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

References

https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-qw58-7h65-crq2

https://www.vulncheck.com/advisories/wasmtime-47.0.0-before-48.0.8-cross-engine-type-confusion-via-structtype-supertype