Which versions of Rancher Fleet are affected by CVE-2026-44937?

Rancher Fleet, a Kubernetes GitOps controller deployed across many organizations, contains an unauthenticated vulnerability allowing attackers to compromise production workloads and disrupt service…. A patch is available.

How to fix or mitigate CVE-2026-44937?

Within 24 hours: Audit all Rancher Fleet deployments to identify webhook endpoints and verify shared-secret authentication is enabled. Within 7 days: Apply security patches per SUSE/Rancher advisory to all Fleet management clusters and validate webhook secret enforcement is active. Within 30 days: Conduct comprehensive security review of all webhook configurations and implement network access restrictions on webhook endpoints as defense-in-depth.

Rancher Fleet CVE-2026-44937

Q: What is the CVSS score of CVE-2026-44937?

CVE-2026-44937 has a CVSS 4.0 base score of 8.3 (High). CVSS vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.2%.

EUVD-2026-41867 HIGH

Insufficient Verification of Data Authenticity (CWE-345)

2026-07-01 https://github.com/rancher/fleet

GHSA-jmf4-m7j9-g72r

Denial Of Service Suse

8.3

CVSS 4.0 · Vendor: https://github.com/rancher/fleet

Severity by source

Vendor (https://github.com/rancher/fleet) PRIMARY

8.3 HIGH

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

6.5 MEDIUM

Network-reachable and unauthenticated because the vulnerable config omits the webhook secret (PR:N), but AC:H reflects regex-crafting/path-knowledge preconditions; main impact is availability DoS (A:H) with limited integrity from downgrade (I:L) and no confidentiality loss.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N

SUSE

HIGH

qualitative

Primary rating from Vendor (https://github.com/rancher/fleet).

CVSS VectorVendor: https://github.com/rancher/fleet

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Lifecycle Timeline

Analysis Updated

Jul 06, 2026 - 11:31 vuln.today

v3 (cvss_changed)

Source Code Evidence Fetched

Jul 06, 2026 - 11:31 vuln.today

Analysis Updated

Jul 06, 2026 - 11:31 vuln.today

v2 (cvss_changed)

Re-analysis Queued

Jul 06, 2026 - 11:22 vuln.today

cvss_changed

CVSS changed

Jul 06, 2026 - 11:22 NVD

7.5 (HIGH) 8.3 (HIGH)

Analysis Generated

Jul 01, 2026 - 21:15 vuln.today

DescriptionCVE.org

Impact

A vulnerability has been identified in Fleet when the webhook endpoint is configured without a secret; an attacker can forge webhook requests. The attacker doesn't need to know the specific repository or path configured in the GitRepo resource to make Fleet process these requests.

An attacker can exploit this vulnerability to cause the following impacts:

Trigger continuous repository re-cloning, which increases network traffic and can deplete resources on the management cluster.
Downgrade running services to any historical revision available in the remote Git repository. This risk applies if the attacker has read access to the target Git repository and knows its configured path.

Please consult the associated MITRE ATT&CK - Technique - T1499.004: Endpoint Denial of Service for further information about this category of attack.

Patches

To resolve this vulnerability, upgrade Fleet to a patched version. This upgrade version escapes the URL and path to the remote repository received from webhooks, which prevents regular expressions from being used as a replacement for the URL and path.

Patched versions of Fleet include releases v0.15.2, v0.14.6, 0.13.11, and v0.12.15.

Workarounds

If you can't upgrade to a fixed version, please make sure to only enable webhooks with a shared secret.

Credits

This security issue was reported by the following collaborators according to our responsible disclosure policy:

Radisauskas Arnoldas from NATO and the NATO Cyber Security Centre (NCSC).

References

If you have any questions or comments about this advisory:

Reach out to the SUSE Rancher Security team for security related inquiries.
Open an issue in the Rancher repository.
Verify with our support matrix and product support lifecycle.

AnalysisAI

Unauthenticated webhook request forgery in Rancher Fleet (GitOps controller for Kubernetes) lets remote attackers manipulate GitRepo processing when the webhook endpoint is configured without a shared secret. Because the repository URL and path received from webhooks are used unsanitized as a regex replacement (CWE-345), an attacker who does not know the configured repository can force continuous re-cloning to exhaust management-cluster resources (DoS), and - if they have read access to the target Git repo and know its path - can downgrade running workloads to any historical revision. No public exploit is identified at time of analysis and it is not listed in CISA KEV; SUSE/Rancher has released fixed versions.

Technical ContextAI

Fleet is Rancher's GitOps engine that continuously reconciles Kubernetes cluster state against Git repositories declared in GitRepo custom resources, running on the management cluster. It exposes an optional webhook receiver so that Git providers (GitHub/GitLab/etc.) can notify Fleet of pushes to trigger immediate re-sync. The root cause (CWE-345, insufficient verification of data authenticity) is twofold: when the webhook is configured without a shared secret, Fleet does not authenticate the sender, and the URL/path values delivered in the webhook payload are interpolated into a regular expression without escaping. This regex-injection allows attacker-supplied values (or wildcard-like regex metacharacters) to match GitRepo resources the attacker could not otherwise name, so a forged request is accepted and acted upon even without knowledge of the exact repository or path. Affected code is the Go module github.com/rancher/fleet.

RemediationAI

Upgrade Fleet to the fixed release for your line - Vendor-released patch: v0.15.2, v0.14.6, 0.13.11, or v0.12.15 - which escapes the URL and path received from webhooks so attacker-supplied values can no longer act as regular-expression replacements. If you cannot upgrade immediately, the vendor-supported workaround is to only enable webhooks that are configured with a shared secret, which restores authentication of incoming webhook requests (side effect: any existing secret-less webhook integrations must be reconfigured with a secret, and the corresponding Git provider webhooks updated to send it). As an additional compensating control, restrict network access to the Fleet webhook endpoint so it is reachable only from the expected Git provider source ranges rather than the open internet. Advisory: https://github.com/rancher/fleet/security/advisories/GHSA-jmf4-m7j9-g72r.