CVE-2026-34040 — moby
HIGHCVE-2026-34040 is a high-severity (CVSS 8.8) CWE-288 vulnerability in github.com/moby/moby. A fix is available for github.com/moby/moby — see the affected versions and patch details below.
Moby: AuthZ plugin bypass with oversized request body
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- 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-2026-34040.
EPSS Exploitation Probability
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.
How urgent is this, really
CVE-2026-34040 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/moby/moby🐹github.com/moby/moby/v2Real-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
Moby is an open source container framework. Prior to version 29.3.1, a security vulnerability has been detected that allows attackers to bypass authorization plugins (AuthZ). This issue has been patched in version 29.3.1.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/moby/moby | all versions | 29.3.1go get github.com/moby/moby@v29.3.1 |
| 🐹Go | github.com/moby/moby/v2 | all versions | 2.0.0-beta.8go get github.com/moby/moby/v2@v2.0.0-beta.8 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/moby/moby, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/moby/moby to 29.3.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34040 is resolved across your whole dependency graph.
Workarounds
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-2026-34040 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-34040. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Multicluster Global Hub 1.4.5 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779579439 | RHSA-2026:22347 |
| Multicluster Global Hub 1.6.5 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1780167118 | RHSA-2026:23345 |
| Multicluster Global Hub 1.7.0 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1779925273 | RHSA-2026:24503 |
| Red Hat multicluster global hub 1.5.3 | multicluster-globalhub/multicluster-globalhub-grafana-rhel9:1778867753 | RHSA-2026:21769 |
Frequently Asked Questions
Is CVE-2026-34040 in your dependencies?
O3 Security finds CVE-2026-34040 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.