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

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-49446
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-15 15:17:16 UTC
Updated2026-09-15 15:17:16 UTC
DescriptionCosmos 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.

Risk And Classification

Primary CVSS: v3.1 6.1 MEDIUM from [email protected]

CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

Problem Types: CWE-285 | CWE-290 | CWE-285 CWE-285: Improper Authorization | CWE-290 CWE-290: Authentication Bypass by Spoofing

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.1MEDIUMCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
3.1CNADECLARED6.1MEDIUMCVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

Attack Vector
Adjacent
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None

CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Azukaar Cosmos-Server affected < 0.22.19 Not specified

References

ReferenceSourceLinkTags
github.com/azukaar/Cosmos-Server/security/advisories/GHSA-2rx5-2g7j-2659 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/azukaar/Cosmos-Server/commit/59c561d686c8f9843b3e092b50f6346c... [email protected] github.com
github.com/azukaar/Cosmos-Server/releases/tag/v0.22.19 [email protected] github.com
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