CVE-2026-126406
Wasmtime before 36.0.20 HTTP Request Smuggling via wasi-http p2 Content-Length
CVSS Score
3.7
EPSS Score
0.0%
EPSS Percentile
0th
The wasmtime-wasi-http p2 implementation in Wasmtime before 36.0.20, 37.0.0 before 48.0.8, 49.0.0 before 49.0.5, and 50.0.0 before 50.0.1 can send conflicting content-length headers, or ones not matching the body, in outgoing requests. A guest that reuses a received response's headers resource to send a bodyless request can enable request smuggling against non-compliant servers, potentially bypassing embedder destination access controls.
| CWE | CWE-444 |
| Vendor | bytecodealliance |
| Product | wasmtime |
| Published | Nov 13, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
bytecodealliance / wasmtime
0 < 36.0.20
bytecodealliance / wasmtime
37.0.0 < 48.0.8
bytecodealliance / wasmtime
49.0.0 < 49.0.5
bytecodealliance / wasmtime
50.0.0 < 50.0.1