CVE-2025-27509: SAML authentication vulnerability due to improper SAML response validation
Impact
In vulnerable versions of Fleet, an attacker could craft a specially-formed SAML response to:
- Forge authentication assertions, potentially impersonating legitimate users. - If Just-In-Time (JIT) provisioning is enabled, the attacker could provision a new administrative user account. - If MDM enrollment is enabled, certain endpoints could be used to create new accounts tied to forged assertions.
This could allow unauthorized access to Fleet, including administrative access, visibility into device data, and modification of configuration.
Patches
This issue is addressed in commit fc96cc4 and is available in Fleet version 4.64.2.
The following backport versions also address this issue:
- 4.63.2 - 4.62.4 - 4.58.1 - 4.53.2
Workarounds
If an immediate upgrade is not possible, Fleet users should temporarily disable single-sign-on (SSO) and use password authentication.
Credit
Thank you @hakivvi, as well as Jeffrey Hofmann and Colby Morgan from the Robinhood Red Team for finding and reporting this vulnerability using our responsible disclosure process.
For more information
If you have any questions or comments about this advisory:
- Email us at security@fleetdm.com - Join #fleet in osquery Slack
Other sources
fleetdm/fleet is an open source device management, built on osquery. In vulnerable versions of Fleet, an attacker could craft a specially-formed SAML response to forge authentication assertions, provision a new administrative user account if Just-In-Time (JIT) provisioning is enabled, or create new accounts tied to forged assertions if f MDM enrollment is enabled. This vulnerability is fixed in 4.64.2, 4.63.2, 4.62.4, and 4.58.1.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
go/github.com/fleetdm/fleet/v4to a version that resolves this vulnerability.Fixed in 4.53.2 - Upgrade
Upgrade
go/github.com/fleetdm/fleet/v4to a version that resolves this vulnerability.Fixed in 4.58.1 - Upgrade
Upgrade
go/github.com/fleetdm/fleet/v4to a version that resolves this vulnerability.Fixed in 4.62.4 - Upgrade
Upgrade
go/github.com/fleetdm/fleet/v4to a version that resolves this vulnerability.Fixed in 4.63.2 - Upgrade
Upgrade
go/github.com/fleetdm/fleet/v4to a version that resolves this vulnerability.Fixed in 4.64.2 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.64.2 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.63.2 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.62.4 - Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Fixed in 4.58.1 - Configuration
Temporarily disable single-sign-on (SSO) in Fleet and use password authentication if an immediate upgrade is not possible.
Fleet (Single-sign-on / SSO) single-sign-on (SSO) = disabled
Event History
Frequently Asked Questions
What is the severity of CVE-2025-27509?
CVE-2025-27509 is a critical vulnerability that allows attackers to craft SAML responses to impersonate legitimate users.
How do I fix CVE-2025-27509?
To fix CVE-2025-27509, upgrade to Fleet version 4.58.1 or any version from 4.62.0 up to 4.64.2.
What are the affected versions for CVE-2025-27509?
CVE-2025-27509 affects Fleet versions between 4.59.0 and 4.64.1, excluding 4.58.1 and specific patches.
Can CVE-2025-27509 lead to new administrative user creation?
Yes, if Just-In-Time (JIT) provisioning is enabled, CVE-2025-27509 can allow attackers to create new administrative accounts.
What type of attack does CVE-2025-27509 enable?
CVE-2025-27509 enables attackers to forge authentication assertions in SAML responses.