CVE-2026-121440
Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 Forwarded Trailers Header Filter Bypass
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.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| wasmtime bytecodealliance wasmtime-wasi-http
cargo |
≥ 46.0.0; < 48.0.7 (affected, semver) 48.0.7 (unaffected, semver) ≥ 49.0.0; < 49.0.4 (affected, semver) 49.0.4 (unaffected, semver) Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 6.3 medium |
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 | CNA: VulnCheck |
| 3.1 / 3.7 low |
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | CNA: VulnCheck |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jxcf-8qw5-5c33CNA: VulnCheck · vendor-advisory
- https://www.vulncheck.com/advisories/wasmtime-46.0.0-before-48.0.7-and-49.0.0-before-49.0.4-forwarded-trailers-header-filter-bypassCNA: VulnCheck · third-party-advisory
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