CVE-2026-34391
Fleetdm Fleet ≤ 4.81.1
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/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:XSummary
CVE-2026-34391 is a medium-severity Exposure of Data Element to Wrong Session (CWE-488) vulnerability in Fleetdm Fleet. Its CVSS base score is 6.6 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Web Session Cookie (T1550.004); ranked at the 6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to AC-3 (Access Enforcement) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-34391 affects Fleet, an open source device management software. In versions prior to 4.81.1, a vulnerability in Fleet's Windows MDM command processing enables a malicious enrolled device to access MDM commands intended for other devices. This exposure can reveal sensitive configuration data, such as WiFi credentials, VPN secrets, and certificate payloads, across the entire Windows fleet. The issue carries a CVSS score of 7.5 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N) and maps to CWE-488.
An attacker with a malicious device enrolled in the Fleet-managed Windows environment can exploit this vulnerability over the network with low complexity and no privileges or user interaction required. Successful exploitation allows the attacker to retrieve MDM commands targeted at other devices, resulting in high-impact unauthorized access to confidential configuration data fleet-wide.
Fleet's security advisory at https://github.com/fleetdm/fleet/security/advisories/GHSA-wg7j-pcc3-h4rh documents the vulnerability. Upgrading to version 4.81.1 patches the issue in the Windows MDM command processing.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-16799
Vulnerability Data
Fleet is open source device management software. Prior to 4.81.1, a vulnerability in Fleet's Windows MDM command processing allows a malicious enrolled device to access MDM commands intended for other devices, potentially exposing sensitive configuration data such as WiFi credentials,…
more
VPN secrets, and certificate payloads across the entire Windows fleet. Version 4.81.1 patches the issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
AC-3 enforces access decisions that can be scoped to the correct session context.
AC-4 controls information flows between entities, reducing cross-session leakage.
SC-4 directly stops unintended transfer of data through shared resources that different sessions may access.
SC-39 isolates execution domains so one session cannot reach another's state or data.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Enforcing authorization policies and least privilege can prevent cross-session data exposure when session separation is treated as an access rule.
Protecting data-in-use directly addresses runtime leakage of session data to unauthorized contexts.
Logical access controls and segmentation can be applied to isolate session state within applications or environments.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing can detect the weakness but does not itself implement the preventive control.
Secure development lifecycle practices include session-management controls that prevent exposure of data to the wrong session.
Application security requirements explicitly call for proper session isolation and state management.
Secure system architecture principles require isolation of session state to avoid cross-session data leakage.
Secure coding standards mandate correct session handling to prevent exposure of data elements to the wrong session.
Information access restriction directly enforces session boundaries so data is not exposed to the wrong session.