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CVE-2026-121440

MediumCVSS 6.3 / 10
Published Nov 3, 2026·Last modified Nov 4, 2026
Affected Components(4)
bytecodealliance/wasmtime
49.0.3
bytecodealliance/wasmtime
49.0.0
bytecodealliance/wasmtime
49.0.1
1 / 2
Description

Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 fails to check forwarded trailers against the WasiHttpHooks::is_forbidden_header hook in wasi-http p3. WASIp3 guests can forward a request or response body so its trailers skip embedder-customized forbidden header filtering, undermining header restrictions the embedder intended.

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Risk Scores
Base Score
6.3

The vulnerability can be exploited over the network without needing physical access. It is difficult for an attacker to exploit this vulnerability and may require special conditions. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability.

Threat Intelligence
1.7

Limited exploitation activity has been observed. Close monitoring and planned remediation are recommended.

EPSS
0.22%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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