CVE-2026-115892
published 2026-10-23CVE-2026-115892: 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…
PriorityP430medium5.7CVSS 4.0
AVNACHATPPRHUIPVCNVINVAHSCNSINSANEXCRXIRXARXMAVXMACXMATXMPRXMUIXMVCXMVIXMVAXMSCXMSIXMSAXSXAUXRXVXREXUX
EPSS
0.43%
37.4th percentile
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
5 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| bytecodealliance | wasmtime | — | — |
| bytecodealliance | wasmtime | — | — |
| bytecodealliance | wasmtime | >= 46.0.0 < 48.0.7 | 48.0.7 |
| bytecodealliance | wasmtime | >= 49.0.0 < 49.0.4 | 49.0.4 |
| rhcl-1 | wasm-shim-rhel9 | — | — |
CVSS provenance
nvdv4.05.7MEDIUMCVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vendor_redhat5.7MEDIUM
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VulDB
Bytecode Alliance Wasmtime up to 48.0.6/49.0.3 Component Model input validation (EUVD-2026-109187)
vuldb·2026-10-23·CVSS 5.7
CVE-2026-115892 [MEDIUM] Bytecode Alliance Wasmtime up to 48.0.6/49.0.3 Component Model input validation (EUVD-2026-109187)
A vulnerability categorized as problematic has been discovered in Bytecode Alliance Wasmtime up to 48.0.6/49.0.3. Affected by this issue is some unknown functionality of the component Component Model. The manipulation results in improper input validation.
This vulnerability is reported as CVE-2026-115892. The attack can be launched remotely. No exploit exists.
It is advisable to upgrade the affected component.
GHSA
Wasmtime: Panic lowering a host-created component model stream into a guest that expects a different payload type
ghsa·2026-10-23
CVE-2026-115892 [MEDIUM] CWE-843 Wasmtime: Panic lowering a host-created component model stream into a guest that expects a different payload type
Wasmtime: Panic lowering a host-created component model stream into a guest that expects a different payload type
### Summary
Wasmtime may panic when the host lowers a component model `stream` or `future` into a guest, if the host created that stream or future with one payload type and the guest expects a different one. This can happen when an embedder creates a stream or future, passes it through a guest, receives it back under a type-erased type such as `StreamAny` or `FutureAny`, and then passes it to a guest function with a different payload type.
GHSA-63h4-6cx9-pjfj is a related advisory also fixing issues within this area, and this advisory is being issued for portions of Wasmtime that were not fixed as part of that advisory.
### Impact
This affects embedders that do all of the
Red Hat
wasmtime: Wasmtime: Denial of Service via missing payload type validation in guest returns
vendor_redhat·2026-10-23·CVSS 5.7
CVE-2026-115892 [MEDIUM] CWE-843 wasmtime: Wasmtime: Denial of Service via missing payload type validation in guest returns
wasmtime: Wasmtime: Denial of Service via missing payload type validation in guest returns
A flaw was found in Wasmtime. A malicious WebAssembly guest can cause a Denial of Service (DoS) by triggering an unhandled host runtime panic. When handling asynchronous streams or futures exchanged between the host and guest, Wasmtime fails to properly validate payload data types upon their return. An untrusted guest can exploit this behavior by manipulating return values with mismatched types, causing the host application to terminate unexpectedly.
Package: rhcl-1/wasm-shim-rhel9 (Red Hat Connectivity Link 1) - Fix deferred
Package: tree-sitter (Red Hat Enterprise Linux 10) - Fix deferred
Package: virt-firmware-rs (Red Hat Enterprise Linux 10) - Fix deferred
No detection rules found.
No public exploits indexed.
https://github.com/bytecodealliance/wasmtime/commit/222ff3a65dab9aa7011f8c246937751a0bac5abdhttps://github.com/bytecodealliance/wasmtime/commit/48dacc76241f06088e79f3ce1b17642f2f7bf158https://github.com/bytecodealliance/wasmtime/commit/994549891c8a706cb4f2809f9d17b9f67b31e618https://github.com/bytecodealliance/wasmtime/pull/14819https://github.com/bytecodealliance/wasmtime/pull/14820https://github.com/bytecodealliance/wasmtime/pull/14827https://github.com/bytecodealliance/wasmtime/releases/tag/v48.0.7https://github.com/bytecodealliance/wasmtime/releases/tag/v49.0.4https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-9pvw-hwfg-92h5
2026-10-23
Published