CVE-2026-121441

EUVD-2026-115863
Wasmtime before 36.0.19, 37.0.0 before 48.0.7, and 49.0.0 before 49.0.4 contains a request smuggling vulnerability in wasi-http that allows guests to set multiple conflicting content-length headers. Malicious guests can make the host send HTTP requests with conflicting content-length values to smuggle requests through servers or intermediaries that do not reject them.
HTTP Request/Response Smuggling
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
𝑥
< 36.0.19
CNA
bytecodealliancewasmtime
37.0.0 ≤
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-r8xh-cgf7-392j
https://www.vulncheck.com/advisories/wasmtime-before-36.0.19-37.0.0-before-48.0.7-and-49.0.0-before-49.0.4-wasi-http-request-smuggling