CVE-2026-115892

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

Published Oct 23, 2026 CVSS 4.0 · 5.7 Medium EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-9pvw-hwfg-92h5 Wasmtime: Panic lowering a host-created component model stream into a guest that expects a different payload type
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Bytecodealliance
Bytecodealliance wasmtime
Vendors & Products Bytecodealliance
Bytecodealliance wasmtime
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate

Type Values Removed Values Added
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.
Title Wasmtime: Panic lowering a host-created component model stream into a guest that expects a different payload type
Weaknesses CWE-248
CWE-843
References
Metrics cvssV4_0

{'score': 5.7, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Oct 29, 2026, 2:44 PM
Reserved
Oct 23, 2026, 7:37 PM
Status
Deferred
Published
Oct 23, 2026, 10:16 PM
Modified
Oct 29, 2026, 3:17 PM
Severity
Moderate
Public date
Oct 23, 2026, 9:26 PM