RUSTSEC-2026-0376 `wasi-http`: Guests can add conflicting content lengths to messages
Not scored
Published
Check this codebase for RUSTSEC-2026-0376 and fix it if it is affected.
What it is: RUSTSEC-2026-0376 is a vulnerability in wasmtime-wasi-http, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of RUSTSEC-2026-0376 in the wild and no public exploit code.
Affected packages and fixed versions:
- wasmtime-wasi-http (crates.io): affected from 0.0.0-0; fixed in 36.0.19, 48.0.7, 49.0.4
Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.
Reference: https://insights.sbomify.com/RUSTSEC-2026-0376/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0376/index.md)
Guests can inject conflicting content lengths in wasi-http messages, potentially causing request smuggling or data integrity issues.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is RUSTSEC-2026-0376?
RUSTSEC-2026-0376 is a vulnerability in wasmtime-wasi-http, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
This is an entry in the RustSec database for the Wasmtime security advisory
located at
https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-r8xh-cgf7-392j
For more information see the GitHub-hosted security advisory.
Which versions are affected by RUSTSEC-2026-0376?
1 open source package ship an affected version, including wasmtime-wasi-http.
| Package | Affected | Fixed in |
|---|---|---|
wasmtime-wasi-http crates.io | From 0.0.0-0 | 36.0.19, 48.0.7, 49.0.4 |
How do I fix RUSTSEC-2026-0376?
Upgrade wasmtime-wasi-http to a fixed version for your release line: 36.0.19, 48.0.7 or 49.0.4.
Is RUSTSEC-2026-0376 being exploited?
There is no known exploitation of RUSTSEC-2026-0376 in the wild and no public exploit code.
Sources
Also known as GHSA-r8xh-cgf7-392j.