CVE-2026-121440

EUVD-2026-115862
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.
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
3.7 LOW
NETWORK
HIGH
NONE
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources (CNA/ADP records, vendor advisories, Enginsight analysis).
VendorProductVersionSource
bytecodealliancewasmtime
46.0.0 ≤
𝑥
< 48.0.7
CNA
bytecodealliancewasmtime
49.0.0 ≤
𝑥
< 49.0.4
CNA
Common Weakness Enumeration
References
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-jxcf-8qw5-5c33
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-bypass