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Medium, CVSS 6.1amended

Cosmos-Server has an authentication bypass via forward-auth header smuggling on Constellation tunnel

CVE-2026-49446GHSA-2rx5-2g7j-2659

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/azukaar/cosmos-server 0.22.19), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
6.1 · CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
EPSS
  • CVE-2026-49446: 0.30% estimated exploitation activity in the next 30 days; percentile 22.69 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary The Constellation-tunnel bypass branch in tokenMiddleware at src/proxy/routerGen.go:53-66 returns to the upstream handler before the request's x-cosmos-user, x-cosmos-role, x-cosmos-user-role, and x-cosmos-mfa headers are stripped at lines 68-72, and before the AdminOnlyWithRedirect gate at lines 109-117 runs. Any holder of a valid Constellation device API key sends x-cosmos-user: admin to a proxied backend; the documented forward-auth integration treats the caller as admin with no JWT cookie, password, or MFA. Preconditions - Cosmos is deployed with Constellation enabled and at least one device enrolled. - Attacker holds a valid x-cstln-auth API key for an enrolled device. - Attacker reaches Cosmos over the Constellation Nebula tunnel. - Target proxy route has AuthEnabled=true; upstream trusts the x-cosmos-user forward-auth header. Details The branch was written for tunneled-cluster traffic where an upstream Cosmos instance has already authenticated the user and signed the…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-2rx5-2g7j-2659

  2. Revision 2 · amended ·

    Amended from osv record GO-2026-6123

  3. Revision 1 · created ·

    Published from osv record GHSA-2rx5-2g7j-2659

Agent brief

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# Patch Next advisory brief: CVE-2026-49446

Advisory: Cosmos-Server has an authentication bypass via forward-auth header smuggling on Constellation tunnel
IDs: CVE-2026-49446, GHSA-2rx5-2g7j-2659
Record: https://patchnext.com/advisories/cve-2026-49446 (revision 3, source checked 26 Oct 2026, 15:27 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/azukaar/cosmos-server 0.22.19. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/azukaar/cosmos-server: affected <= 0.22.18; fixed in 0.22.19

## Suggested inspection (read-only)
- Go github.com/azukaar/cosmos-server: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/azukaar/cosmos-server.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-2rx5-2g7j-2659 (OSV record GHSA-2rx5-2g7j-2659 lists affected ranges: Go github.com/azukaar/cosmos-server >=0 <0.22.19 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6123 (OSV record GO-2026-6123 lists affected ranges: Go github.com/azukaar/cosmos-server >=0 <0.22.19 (fixed))
- Verified: https://github.com/advisories/GHSA-2rx5-2g7j-2659 (GitHub-reviewed advisory GHSA-2rx5-2g7j-2659 lists affected ranges: Go github.com/azukaar/cosmos-server >=0 <=0.22.18)

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