Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 panics when the host reads a component model stream as a different Rust item type than it was created with, because the host-to-host read path asserts matching TypeIds instead of returning an error. Guest code can return a host-created StreamReader<U> that the embedder reads as StreamReader<T>, where both types map to the same component model type, crashing the embedding process.

Attack Vector Network

Attack Complexity High

Privileges Required Low

Attack Requirements Present

User Interaction Passive

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
bytecodealliance wasmtime unaffected
Version Status Constraints
46.0.0 affected < 48.0.6
48.0.6 unaffected —
49.0.0 affected < 49.0.3
49.0.3 unaffected —

No data.

No data.

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Project Subscriptions

Vendors Products
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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-63h4-6cx9-pjfj cve-icon cve-icon
https://www.vulncheck.com/advisories/wasmtime-46.0.0-before-48.0.6-and-49.0.0-before-49.0.3-panic-via-streamreader-type-mismatch cve-icon cve-icon
History

Thu, 29 Oct 2026 16:15:00 +0000

Type Values Removed Values Added
Description Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 panics when the host reads a component model stream as a different Rust item type than it was created with, because the host-to-host read path asserts matching TypeIds instead of returning an error. Guest code can return a host-created StreamReader<U> that the embedder reads as StreamReader<T>, where both types map to the same component model type, crashing the embedding process.
Title Wasmtime 46.0.0 before 48.0.6 and 49.0.0 before 49.0.3 Panic via StreamReader Type Mismatch
First Time appeared Bytecodealliance
Bytecodealliance wasmtime
Weaknesses CWE-617
CPEs cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:*:*:*
Vendors & Products Bytecodealliance
Bytecodealliance wasmtime
References
Metrics cvssV3_1

{'score': 4.8, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 5.9, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N'}

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

Updated: 2026-10-29T15:58:15.914Z

Reserved: 2026-10-29T14:26:15.522Z

Link: CVE-2026-119135

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Deferred

Published: 2026-10-29T16:18:06.757

Modified: 2026-10-29T16:18:06.870

Link: CVE-2026-119135

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-29T18:00:17Z

Weaknesses