Juju has broken CMR authorization

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS 4.0

2.1 · CVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L · score source

EPSS

• CVE-2026-1237: 0.14% estimated exploitation activity in the next 30 days; percentile 3.54 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact Cross-model Relation authorization is broken and has a potential security vulnerability. If the controller does not have the root key to verify the macaroon (or if the macaroon has expired), an unvalidated and therefore untrusted macaroon is used to extract declared caveats. Facts from these caveats are then blindly used to mint a new macaroon that becomes valid. Scenario A user knows that user X has access to offer Y. The user mints a macaroon stating that user X has access to offer Y and sends it to the controller in a request. The controller fails to verify the macaroon because it lacks the root key and mints a new macaroon requiring proof that user X has access to offer Y. Since user X does have access and the discharge endpoint does not require authentication, the controller returns the new macaroon. The user can then use the returned macaroon to consume the offer as user X. Patches N/A Workarounds A previous proposal via this PR addresses the issue but would break model…

Published by the source

29 Jan 2026, 15:21 UTC

Last modified by the source

29 Jan 2026, 15:21 UTC

Source last checked

26 Oct 2026, 15:14 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-j477-6vpg-6c8x

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# Patch Next advisory brief: CVE-2026-1237

Advisory: Juju has broken CMR authorization
IDs: CVE-2026-1237, GHSA-j477-6vpg-6c8x
Record: https://patchnext.com/advisories/cve-2026-1237 (revision 1, source checked 26 Oct 2026, 15:14 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 2.1)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor response not established. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/juju/juju: affected <= 0.0.0-20260127110037-9b1a0e53a4a4

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

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/juju/juju.
- 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://github.com/advisories/GHSA-j477-6vpg-6c8x (GitHub-reviewed advisory GHSA-j477-6vpg-6c8x lists affected ranges: Go github.com/juju/juju >=0 <=0.0.0-20260127110037-9b1a0e53a4a4)

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