CVE-2026-49446: Access Control Flaw (CVSS 6.1)

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.

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CVSS v3.1 Score

6.1

MEDIUM

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

EPSS — Exploit Prediction

0.0029

Probability of exploitation

0.21%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-285 CWE-285

CWE-290 CWE-290

References

Other 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

Frequently Asked Questions

What is CVE-2026-49446? +

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. It has a CVSS v3.1 base score of 6.1 (MEDIUM).

How severe is CVE-2026-49446? +

CVE-2026-49446 has a CVSS v3.1 score of 6.1 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0029, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-49446? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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