How severe is CVE-2026-1237?

No CVSS score has been assigned to CVE-2026-1237 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-1237?

CVE-2026-1237 affects the following packages: github.com/juju/juju (Go). Ecosystems affected: Go.

How do I fix CVE-2026-1237?

No patched version of github.com/juju/juju has shipped for CVE-2026-1237 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

How do I detect CVE-2026-1237 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/juju/juju, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-1237 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-1237?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-1237 can be triaged on real exposure rather than presence alone.

Is CVE-2026-1237 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-1237 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-1237?

CVE-2026-1237 has an EPSS (Exploit Prediction Scoring System) score of 0.1%, placing it in the 3th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-1237?

CVE-2026-1237 is classified as CWE-347 (CWE-347), CWE-672 (CWE-672). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-1237 published, and has it been updated?

CVE-2026-1237 was published on January 29, 2026 and was last updated on February 3, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹 Go

Not in CISA KEV

CVE-2026-1237 — juju

Fix: juju/juju#21062

CVE-2026-1237 is a CWE-347 vulnerability in github.com/juju/juju. No vendor fix is recorded yet; mitigation options are listed below.

Juju has broken CMR authorization

Also known asGO-2026-4388

Published

Jan 29, 2026

Updated

Feb 3, 2026

Affected

1 pkg

Patched

See advisory

Exploits

None indexed

Exploitation data as of Sep 21, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-1237.

EPSS Exploitation Probability

via FIRST.org ↗

0.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs3th percentile — riskier than 3% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected

🐹github.com/juju/juju

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

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 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.

Affected Packages

1 total

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/juju/juju`	all versions	No fix

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/juju/juju, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Remediation status
No patched version of github.com/juju/juju has shipped for CVE-2026-1237 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-1237 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-1237. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### 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 be

O3 Security · Impact-Aware SCA

Is CVE-2026-1237 in your dependencies?

O3 Security finds CVE-2026-1237 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works