CVE-2026-126408

Description

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.

Severity scores

Each score is shown as its source gave it. They are not averaged or merged.

• 1.0CVSS 4.0, Lowfrom the CNA (VulnCheck)CVSS:4.0/AV:A/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
• 1.8CVSS 3.1, Lowfrom the CNA (VulnCheck)CVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:U/C:N/I:N/A:L

Historical context and remediation

This reference retains the original CVE publication date. A recent record update does not mean a new attack occurred.

No separately sourced impact summary is available on this page yet. Consult the description, version data and dated exploitation evidence.

No explicit remediation statement is available on this page yet. Consult the original record and vendor references before choosing a fix.

Version statuses below come from the CNA. An “unaffected” version is not necessarily a currently supported release or proof of a patch date. EPSS is a dated risk estimate, not a count of historical attacks.

Read the original CVE record.

Affected products

Timeline

1. 13 Nov 2026 Published

Weakness

• CWE-617

References

• GitHub Security Advisory (GHSA-3982-jqvv-277m)vendor-advisory
• VulnCheck Advisory: Wasmtime 47.0.0 before 48.0.8 Denial of Service via TypedFunc Type-Check Panicthird-party-advisory