What’s Vulnerable › Vulnerabilities

CVE-2026-115892: Wasmtime: Panic lowering a host-created component model stream into a guest that expects a different payload type

• Severity: medium (CVSS 5.7 v4.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-23 · updated 2026-10-29
• Weakness: CWE-248

Description

Wasmtime is a runtime for WebAssembly. From 46.0.0 until 48.0.7 and 49.0.4, lowering a host-created component-model stream or future into a guest can omit a required payload-type check after the value passes through guest code and returns through StreamAny, FutureAny, Val::Stream, Val::Future, or an equivalent typed reader. A malicious guest that controls exported function types or returned values can cause the host to pass the type-erased value to a guest expecting a different payload type, which panics the Wasmtime host. This issue is fixed in versions 48.0.7 and 49.0.4.

Affected products

• bytecodealliance wasmtime: from 46.0.0, < 48.0.7; from 49.0.0, < 49.0.4

References

• https://github.com/bytecodealliance/wasmtime/commit/222ff3a65dab9aa7011f8c246937751a0bac5abd
• https://github.com/bytecodealliance/wasmtime/commit/48dacc76241f06088e79f3ce1b17642f2f7bf158
• https://github.com/bytecodealliance/wasmtime/commit/994549891c8a706cb4f2809f9d17b9f67b31e618
• https://github.com/bytecodealliance/wasmtime/pull/14819
• https://github.com/bytecodealliance/wasmtime/pull/14820
• https://github.com/bytecodealliance/wasmtime/pull/14827
• https://github.com/bytecodealliance/wasmtime/releases/tag/v48.0.7
• https://github.com/bytecodealliance/wasmtime/releases/tag/v49.0.4
• https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-9pvw-hwfg-92h5

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