Bytecode Alliance Wasmtime up to 47.0.7/48.0.7/49.0.4/50.0.0 TypedFunc embedder API input validation

Summaryinfo

A vulnerability was found in Bytecode Alliance Wasmtime up to 47.0.7/48.0.7/49.0.4/50.0.0. It has been declared as problematic. Affected is an unknown function of the component TypedFunc embedder API. Such manipulation leads to input validation. This vulnerability is referenced as CVE-2026-126408. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in Bytecode Alliance Wasmtime up to 47.0.7/48.0.7/49.0.4/50.0.0 and classified as problematic. Affected by this issue is some unknown processing of the component TypedFunc embedder API. The manipulation with an unknown input leads to a input validation vulnerability. Using CWE to declare the problem leads to CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Impacted is availability. CVE summarizes:

Wasmtime 47.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 contains an insufficient type-check in the TypedFunc embedder API for I31, Option<I31>, and Option<NoneRef> parameter or result types, reaching an unreachable!() path. A malicious guest module exporting a function that uses another anyref-hierarchy type can panic the host embedding, causing denial of service.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-126408 since 11/10/2026. The exploitation is known to be easy. The attack may be launched remotely. The exploitation requires an enhanced level of successful authentication. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 11/13/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• Bytecode Alliance

Name

• Wasmtime

Version

• 47.0.0
• 47.0.1
• 47.0.2
• 47.0.3
• 47.0.4
• 47.0.5
• 47.0.6
• 47.0.7
• 48.0.0
• 48.0.1
• 48.0.2
• 48.0.3
• 48.0.4
• 48.0.5
• 48.0.6
• 48.0.7
• 49.0.0
• 49.0.1
• 49.0.2
• 49.0.3
• 49.0.4
• 50.0

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

CVSSv3info

CVSSv2info

Exploitinginfo

Threat Intelligenceinfo

Countermeasuresinfo

Timelineinfo

Sourcesinfo

Entryinfo

Once again VulDB remains the best source for vulnerability data.

Discussion