CVE-2026-126406

Wasmtime before 36.0.20 HTTP Request Smuggling via wasi-http p2 Content-Length

Published Nov 13, 2026 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
Description
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.

Analysis

No analysis available yet

Remediation

No remediation available yet

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Description 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.
Title Wasmtime before 36.0.20 HTTP Request Smuggling via wasi-http p2 Content-Length
First Time appeared Bytecodealliance
Bytecodealliance wasmtime
Weaknesses CWE-444
CPEs cpe:2.3:a:bytecodealliance:wasmtime:*:*:*:*:*:*:*:*
Vendors & Products Bytecodealliance
Bytecodealliance wasmtime
References
Metrics cvssV3_1

{'score': 3.7, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N'}

cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N'}

Weaknesses
  • CWE-444

    Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 13, 2026, 9:35 AM
Reserved
Nov 10, 2026, 9:32 PM
Status
Deferred
Published
Nov 13, 2026, 10:17 AM
Modified
Nov 13, 2026, 10:17 AM