# CVE-2026-1237: Juju has broken CMR authorization

> A malicious user can mint invalid macaroons to bypass revoked cross-model permissions, allowing unauthorized charm relations and workload access.

- **Severity:** Low 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`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 28 Jan 2026
- **Updated:** 28 Jan 2026
- **Also known as:** GHSA-j477-6vpg-6c8x, GO-2026-4388

## What is CVE-2026-1237?

CVE-2026-1237 is a low-severity authentication bypass vulnerability in Canonical juju, published on 28 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Vulnerable cross-model authorization in juju. If a charm's cross-model permissions are revoked or expire, a malicious user who is able to update database records can mint an invalid macaroon that is incorrectly validated by the juju controller, enabling a charm to maintain otherwise revoked or expired permissions. This allows a charm to continue relating to another charm in a cross-model relation, and use their workload without their permission. No fix is available as of the time of writing.

Weakness: CWE-672 (Operation on a Resource after Expiration or Release), CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2026-1237?

3 open source packages ship an affected version, including github.com/juju/juju.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/juju/juju` | Go | All versions | None |
| `github.com/juju/juju` | Go | All versions to 0.0.0-20260127110037-9b1a0e53a4a4 | None |
| `github.com/juju/juju` | Go | All versions to 0.0.0-20260127110037-9b1a0e53a4a4 | None |

## How do I fix CVE-2026-1237?

No fix published yet.

## Is CVE-2026-1237 being exploited?

There is no known exploitation of CVE-2026-1237 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-1237 and fix it if it is affected.

What it is: CVE-2026-1237 is a low-severity authentication bypass vulnerability in Canonical juju, published on 28 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-1237 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/juju/juju (Go): affected all versions; no fix listed
- github.com/juju/juju (Go): affected all versions up to 0.0.0-20260127110037-9b1a0e53a4a4; no fix listed
- github.com/juju/juju (Go): affected all versions up to 0.0.0-20260127110037-9b1a0e53a4a4; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-1237/ (Markdown: https://insights.sbomify.com/CVE-2026-1237/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-1237
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-1237
- OSV: https://osv.dev/vulnerability/CVE-2026-1237

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-1237/
Summaries are generated and may contain mistakes; the official description above is the record.