What’s Vulnerable › Vulnerabilities

CVE-2026-49446: Cosmos: Authentication bypass via forward-auth header smuggling on Constellation tunnel in Cosmos-Server

• Severity: medium (CVSS 6.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-15 · updated 2026-09-30
• Weakness: CWE-285

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.

Affected products

• azukaar Cosmos-Server: before 0.22.19

References

• https://github.com/azukaar/Cosmos-Server/commit/59c561d686c8f9843b3e092b50f6346c481d8bbf
• https://github.com/azukaar/Cosmos-Server/releases/tag/v0.22.19
• https://github.com/azukaar/Cosmos-Server/security/advisories/GHSA-2rx5-2g7j-2659
• https://github.com/azukaar/Cosmos-Server/security/advisories/GHSA-2rx5-2g7j-2659

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