CVE-2026-1237: Github.com/juju/juju Juju Has Broken CMR Authorization Vulnerability

LOW
Advisory Identifier: GHSA-j477-6vpg-6c8x
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CWE-347
Published
Advisory Summary

CVE-2026-1237 is a LOW juju has broken cmr authorization vulnerability (CWE-347: Improper Verification of Cryptographic Signature) affecting Github.com/juju/juju libraries in the Go ecosystem. The issue involves juju has broken cmr authorization. Remediation is available in the latest vendor maintenance releases.

CVE-2026-1237 at a Glance

CVE Identifier CVE-2026-1237
GHSA Identifier GHSA-j477-6vpg-6c8x
Severity LOW
CVSS v3.1 Base Score N/A
CWE Classification CWE-347: Improper Verification of Cryptographic Signature
Affected Product Github.com/juju/juju
Package Ecosystem Go
Published Date
Last Updated

How to Fix CVE-2026-1237

To remediate this vulnerability, upgrade all affected Github.com/juju/juju dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/juju/juju fixed: Latest secure release 
Upgrade github.com/juju/juju to Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/juju/juju

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-1237, inspect your project dependencies for Github.com/juju/juju:

inspect dependencies for github.com/juju/juju

Analyze the terminal output to locate any version of Github.com/juju/juju in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-347: Improper Verification of Cryptographic Signature, where the product does not verify, or incorrectly verifies, the cryptographic signature for data. In Github.com/juju/juju, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### 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](https://github.com/juju/juju/pull/21062) addresses the issue but would break model migrations since macaroon root keys are not included in model descriptions. Additionally, root keys are not model-scoped, making it unclear which keys to transfer during migration.

CVE-2026-1237 Affected Github.com/juju/juju Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
github.com/juju/juju
golang/github.com/juju/juju
Go
≤ 0.0.0-20260127110037-9b1a0e53a4a4

References

Github.com/juju/juju Source Repository REPOSITORY
https://github.com/juju/juju/pull/21062
Github.com/juju/juju Source Repository REPOSITORY
https://github.com/juju/juju
GitHub Advisory / Wiki ADVISORY
https://github.com/juju/juju/security/advisories/GHSA-j477-6vpg-6c8x
NVD — CVE-2026-1237 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-1237

Frequently Asked Questions

What is CVE-2026-1237?
CVE-2026-1237 is a security vulnerability in Github.com/juju/juju involving Juju has broken CMR authorization under CWE-347: Improper Verification of Cryptographic Signature.
Which Github.com/juju/juju versions are affected?
Affected versions include releases prior to current release patches across affected packages: github.com/juju/juju.
What version fixes CVE-2026-1237?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/juju/juju affected?
Yes, github.com/juju/juju is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What CWE is associated with CVE-2026-1237?
CVE-2026-1237 is classified under CWE-347: Improper Verification of Cryptographic Signature (The product does not verify, or incorrectly verifies, the cryptographic signature for data.).
How can I check Go dependencies for CVE-2026-1237?
Run the dependency tree command: 'inspect dependencies for github.com/juju/juju'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-j477-6vpg-6c8x",
  "modified" : "2026-01-29T15:21:27Z",
  "published" : "2026-01-29T15:21:27Z",
  "aliases" : [ "CVE-2026-1237" ],
  "summary" : "Juju has broken CMR authorization",
  "details" : "### Impact\n\nCross-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.\n\n### Scenario\n\nA 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.\n\n### Patches\n\nN/A\n\n### Workarounds\n\nA previous proposal via [this PR](https://github.com/juju/juju/pull/21062) addresses the issue but would break model migrations since macaroon root keys are not included in model descriptions. Additionally, root keys are not model-scoped, making it unclear which keys to transfer during migration.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/juju/juju"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "last_affected" : "0.0.0-20260127110037-9b1a0e53a4a4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/juju/juju/security/advisories/GHSA-j477-6vpg-6c8x"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-1237"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/juju/juju/pull/21062"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/juju/juju"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-347" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-29T15:21:27Z",
    "nvd_published_at" : "2026-01-28T15:16:16Z"
  }
}