Cosmos: Authentication bypass via forward-auth header smuggling on Constellation tunnel in Cosmos-Server (CVE-2026-49446) | HOL Guard CVE

Medium severityCVE-2026-49446GHSA-2RX5-2G7J-2659

Cosmos: Authentication bypass via forward-auth header smuggling on Constellation tunnel in Cosmos-Server

Answer in brief

CVE-2026-49446 records a Medium severity vulnerability in Cosmos: Authentication bypass via forward-auth header smuggling on Constellation tunnel in Cosmos-Server. The current sources do not mark it as known exploited. The current feed maps azukaar/Cosmos-Server (generic), github.com/azukaar/cosmos-server (go). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Sep 15, 2026Updated Sep 15, 2026Source checked Sep 15, 2026First seen by HOL Aug 2, 2026Material review Sep 15, 2026

Upstream Advisory

Key facts

Risk: Medium
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps azukaar/Cosmos-Server (generic), github.com/azukaar/cosmos-server (go). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
azukaar/Cosmos-Servergeneric	< 0.22.19	Not reported
github.com/azukaar/cosmos-servergo	<=0.22.18	0.22.19

Recommended response

Check inventory. Check lockfiles and deployed manifests for azukaar/Cosmos-Server, github.com/azukaar/cosmos-server.
Review the reported fix. Update github.com/azukaar/cosmos-server to 0.22.19 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 15, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 15, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 2, 2026

Sources and claim methodology

Upstream source description

Cosmos provides users the ability self-host a home server by acting as a secure gateway to your application, as well as a server manager. Prior to 0.22.19, tokenMiddleware in src/proxy/routerGen.go can return through the Constellation tunnel bypass before removing x-cosmos-user, x-cosmos-role, x-cosmos-user-role, and x-cosmos-mfa headers and before invoking AdminOnlyWithRedirect. An attacker with a valid x-cstln-auth API key for an enrolled device who reaches Cosmos through the Constellation Nebula tunnel can supply a chosen x-cosmos-user value to a route with AuthEnabled enabled when the upstream application trusts that forward-auth header. The request can bypass Cosmos JWT, password, MFA, and AdminOnly checks, allowing user impersonation and admin-tier reads or writes exposed by the proxied application. This issue is fixed in version 0.22.19.

Quoted source text, attributed separately from HOL analysis.