# RUSTSEC-2026-0377: `wasi-http` p3: forwarded trailers aren't checked against `is_forbidden_header` hook

> Attackers can bypass header restrictions in wasi-http by sending forbidden forwarded trailers, potentially violating security policies.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Oct 2026
- **Also known as:** GHSA-jxcf-8qw5-5c33

## What is RUSTSEC-2026-0377?

RUSTSEC-2026-0377 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-jxcf-8qw5-5c33
For more information see the GitHub-hosted security advisory.

## Which versions are affected by RUSTSEC-2026-0377?

1 open source package ship an affected version, including wasmtime-wasi-http.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `wasmtime-wasi-http` | crates.io | From 46.0.0 | 48.0.7, 49.0.4 |

## How do I fix RUSTSEC-2026-0377?

Upgrade wasmtime-wasi-http to a fixed version for your release line: 48.0.7 or 49.0.4.

## Is RUSTSEC-2026-0377 being exploited?

There is no known exploitation of RUSTSEC-2026-0377 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for RUSTSEC-2026-0377 and fix it if it is affected.

What it is: RUSTSEC-2026-0377 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-2026-0377 in the wild and no public exploit code.

Affected packages and fixed versions:
- wasmtime-wasi-http (crates.io): affected from 46.0.0; fixed in 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-2026-0377/ (Markdown: https://insights.sbomify.com/RUSTSEC-2026-0377/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/RUSTSEC-2026-0377

---
From sbomify Insights: https://insights.sbomify.com/RUSTSEC-2026-0377/
Summaries are generated and may contain mistakes; the official description above is the record.