CVE-2026-121439
Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 HTTP Response Splitting via wasi-http
CVSS Score
5.3
EPSS Score
0.0%
EPSS Percentile
0th
Wasmtime 46.0.0 before 48.0.7 and 49.0.0 before 49.0.4 contains a response splitting vulnerability in wasi-http p3 that allows guests to set unvalidated content-length headers. Malicious wasip3 guests can splice an existing body into a new response with an incorrect content-length to perform response splitting or injection attacks.
| CWE | CWE-444 |
| Vendor | bytecodealliance |
| Product | wasmtime |
| Published | Nov 3, 2026 |
Stay Ahead of the Next One
Get instant alerts for bytecodealliance wasmtime
Be the first to know when new medium vulnerabilities affecting bytecodealliance wasmtime are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
bytecodealliance / wasmtime
46.0.0 < 48.0.7 49.0.0 < 49.0.4