CVE-2026-32881 ewe has an Overly Permissive List of Allowed Inputs
Attackers can bypass authentication and hijack sessions by spoofing headers via chunked transfer encoding trailers in the ewe web server.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-32881?
CVE-2026-32881 is a medium-severity authentication bypass vulnerability in vshakitskiy ewe, published on 20 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
ewe is a Gleam web server. ewe is a Gleam web server. Versions 0.6.0 through 3.0.4 are vulnerable to authentication bypass or spoofed proxy-trust headers. Chunked transfer encoding trailer handling merges declared trailer fields into req.headers after body parsing, but the denylist only blocks 9 header names. A malicious client can exploit this by declaring these headers in the Trailer field and appending them after the final chunk, causing request.set_header to overwrite legitimate values (e.g., those set by a reverse proxy). This enables attackers to forge authentication credentials, hijack sessions, bypass IP-based rate limiting, or spoof proxy-trust headers in any downstream middleware that reads headers after ewe.read_body is called. This issue has been fixed in version 3.0.5.
Weakness: CWE-183
Which versions are affected by CVE-2026-32881?
2 open source packages ship an affected version, including ewe. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
ewe Hex | From 0.6.0 | 3.0.5 |
ewe Hex | From 0.6.0 | 3.0.5 |
Products include Vshakitskiy Ewe.
How do I fix CVE-2026-32881?
Upgrade ewe to 3.0.5 or later.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-32881 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-32881 exists.
Other vulnerabilities in vshakitskiy ewe
Sources
Also known as GHSA-9w88-79f8-m3vp.