GHSA-2rc4-7jc6-qffh CVE-2026-23998 GO-2026-5002
Fleet has a Windows MDM management endpoint authentication bypass
- Severity
- 0.0 / 10
- High · CVSS 4.0
- Exploit chance (EPSS)
- 0.21%
- Chance of exploitation in the next 30 days. Higher than 11.82% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-295 Improper Certificate Validation
- Fix
4.81.0- Upgrade github.com/fleetdm/fleet/v4 to this version or later
Description
Summary
A vulnerability in Fleet’s Windows MDM management endpoint could allow requests to be processed without proper client certificate validation. In certain circumstances, this could allow an attacker to impersonate an enrolled Windows device and retrieve sensitive configuration data.
Impact
Fleet’s Windows MDM management endpoint relies on mutual TLS (mTLS) client certificates to authenticate enrolled devices. In affected versions, requests that did not present a client certificate could be incorrectly treated as trusted.
As a result, an attacker with prior knowledge of a valid enrolled device identifier could potentially impersonate that device and receive configuration payloads intended for it. These payloads may contain sensitive information such as Wi-Fi or VPN configuration data, certificates, or other secrets delivered through MDM profiles.
This issue does not allow enrollment of new devices, administrative access to Fleet, or compromise of the Fleet control plane. Impact is limited to the targeted Windows device.
Workarounds
If an immediate upgrade is not possible, affected Fleet users should temporarily disable Windows MDM.
For more information
If you have any questions or comments about this advisory:
Email us at security@fleetdm.com Join #fleet in osquery Slack
Credits
We thank @secfox-ai for responsibly reporting this issue.
Affected versions
Go
| Package | Vulnerable | Fixed in |
|---|---|---|
| github.com/fleetdm/fleet/v4 | < 4.81.0 |
4.81.0 |
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
github.com/fleetdm/fleet/v4 Go → 4.81.0
- go
go get github.com/fleetdm/fleet/v4@v4.81.0 && go mod tidy
Severity breakdown
CVSS 4.0 0.0
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- Attack vector
- Network
- Attack complexity
- High
- Attack requirements
- None
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- High
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- None
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
CVSS 3.1 7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
Weakness
CWE-295: Improper Certificate Validation
The product does not validate, or incorrectly validates, a certificate.
How to prevent it
- Architecture and Design, Implementation: Certificates should be carefully managed and checked to assure that data are encrypted with the intended owner's public key.
- Implementation: If certificate pinning is being used, ensure that all relevant properties of the certificate are fully validated before the certificate is pinned, including the hostname.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-rxhg-vcww-2mpw Fleet: ORDER BY column injection on activity list endpoints | Low | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-q9c5-pp7m-fm2g Fleet: Unauthenticated download of in-house iOS app binaries via predictable URLs | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GO-2026-6264 Fleet: SQL injection in Okta conditional access endpoint allows host-controlled compromise of the Fleet database | High | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-88p2-jj8w-j8qg Fleet: Observer-class users can view team enroll secrets and credential-bearing configuration via target search endpoint | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-gm7f-v959-fr2g Fleet DM Vulnerable to Cross-Team Policy Data Exposure via Global Policy Read Endpoint | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-x4qr-qw6h-wvxq Fleet: Observer-level enrollment secret extraction via ORDER BY oracle on Apple MDM commands endpoint | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-vxm7-9x8v-8gm4 Fleet has observer-level enrollment secret extraction via ORDER BY oracle on labels host-listing endpoint | Medium | Also affects github.com/fleetdm/fleet/v4 |
| GHSA-mxmp-wr3w-rvqx Fleet: IP spoofing allows bypassing API rate limiting | High | Also affects github.com/fleetdm/fleet/v4 |
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