Vulnerability Summary

Field	Details
CVE ID	CVE-2026-25604
Vulnerability Name	AWS Auth Manager SAML Authentication Origin Validation Bypass
Affected Software	Apache Airflow – Amazon Provider (AWS Auth Manager)
Affected Versions	apache-airflow-providers-amazon 8.0.0 – 9.21.x
Patched Version	9.22.0 and later
Vulnerability Type	Authentication Bypass / Host Header Manipulation
Attack Vector	Network
Privileges Required	None
User Interaction	Required during authentication flow
Severity	High
CVSS Score	~8.0 (Estimated)
Exploitability	Moderate to High
Exploit Availability	No public exploit framework, but exploitation can be reproduced manually
Impact	Unauthorized login to Airflow instance via reused SAML authentication response

A vulnerability was identified in the AWS Auth Manager component used by the Apache Airflow Amazon provider package. The issue occurs because the origin of the SAML authentication request is taken directly from the client request and is not verified against the configured Airflow instance URL. This behavior allows manipulation of host or origin headers during the authentication process and can result in SAML responses being reused across instances.

Overview

Apache Airflow environments that use the AWS Auth Manager with SAML authentication are affected by this issue. The authentication flow relies on SAML assertions generated by an Identity Provider (IdP). Normally, the application must verify that the SAML response was intended for the exact service provider instance that initiated the authentication request.

In vulnerable implementations, the origin value used during authentication is derived from client-supplied headers rather than the actual configured instance URL. Because of this behavior, the application may incorrectly trust a SAML assertion even if it was originally issued for another Airflow instance.

If the request headers are manipulated, the system may accept a SAML authentication response that was not meant for that specific deployment. This effectively creates a situation where authentication responses may be replayed or reused across instances.

Technical Root Cause

The vulnerability exists due to improper validation during the SAML authentication workflow.

During the authentication process:

A user attempts to log into the Airflow interface.
The request is redirected to the Identity Provider.
The IdP generates a signed SAML assertion.
The assertion is returned to the Airflow authentication endpoint.
The AWS Auth Manager determines the authentication origin using request headers supplied by the client.

Instead of validating the origin against the configured Airflow instance address, the application relies on the value provided in the HTTP request. Because these headers can be controlled by an attacker, the verification logic can be bypassed.

As a result, authentication assertions may be accepted even if they were generated for a different environment.

Affected Environment

The vulnerability affects environments that meet the following conditions:

Apache Airflow deployment using AWS Auth Manager
SAML authentication enabled
Apache Airflow Amazon provider package between 8.0.0 and 9.21.x

Typical deployments include:

Kubernetes Airflow clusters
Self-hosted Airflow servers
Cloud hosted Airflow environments
Enterprise Airflow platforms integrated with SAML SSO

Identity providers commonly used with these deployments include:

AWS IAM Identity Center
Okta
Azure AD
Other SAML compatible identity providers

Exploitation Scenario

A successful attack relies on the ability to replay a valid SAML response or manipulate request headers.

Example attack sequence

A valid SAML authentication response is obtained.
This may occur through interception, logging exposure, or testing environments.
A request is crafted toward a vulnerable Airflow instance.
Request headers such as Host or X-Forwarded-Host are manipulated to modify the origin.
The captured SAML response is replayed during the authentication flow.
Because the origin is not validated against the real instance URL, the assertion is accepted.
The attacker is granted authenticated access to the Airflow interface.

This attack does not necessarily require credential theft. The primary weakness lies in the trust placed on the request origin.

Proof of Concept (Educational Use Only)

The following example illustrates how the vulnerability could be tested in a controlled environment.

Sample request replay

POST /aws-auth/saml/acs HTTP/1.1
Host: airflow-target.internal
X-Forwarded-Host: malicious.example.com
Content-Type: application/x-www-form-urlencodedSAMLResponse=<Base64EncodedAssertion>
RelayState=airflow

If the application relies on the manipulated header when validating the SAML response, authentication may succeed even though the assertion was not issued for that instance.

Testing should only be performed in controlled environments with proper authorization.

Impact

If exploited successfully, the following consequences may occur:

Unauthorized Access

Attackers may gain access to the Airflow web interface without valid credentials.

Privilege Escalation

If the reused SAML assertion belongs to a privileged user, administrative functions may become accessible.

Workflow Manipulation

Airflow DAGs may be triggered, modified, or deleted.

Data Exposure

Sensitive information stored within Airflow configurations or connections may be accessed.

Infrastructure Risk

Airflow pipelines frequently interact with cloud infrastructure, including:

databases
storage services
internal APIs
container orchestration systems

Compromise of Airflow may therefore expose additional internal systems.

Indicators of Exploitation

Security monitoring may reveal several indicators associated with this vulnerability.

Abnormal Authentication Origins

Authentication attempts referencing unexpected domain names.

Host Header Manipulation

Requests containing conflicting host related headers.

Example:

Host: airflow.company.internal
X-Forwarded-Host: attacker-domain.example

Repeated SAML Assertion Usage

Multiple successful logins referencing the same assertion ID.

Authentication From Unexpected Sources

Detection

Application Log Analysis

Search for authentication events where request headers do not match the configured service URL.

Example query logic:

authentication_event
| where request_host != airflow_instance_domain

Splunk Detection Query

index=airflow_logs
"saml" AND ("Host" OR "X-Forwarded-Host")
| eval mismatch=if(host!=configured_domain,1,0)
| search mismatch=1

Elastic Detection Query

event.dataset:airflow.auth AND
(http.request.headers.host:* AND http.request.headers.x_forwarded_host:*)
AND NOT http.request.headers.host.keyword:expected_airflow_domain

Microsoft Sentinel (KQL)

AirflowLogs
| where EventType == "Authentication"
| where HostHeader != InstanceDomain
| summarize count() by HostHeader, SourceIP

Generic SIEM Logic

IF authentication_event
AND host_header != configured_service_provider_domain
THEN generate alert

Log Sources

Monitoring should include the following log sources.

Application Logs

Airflow authentication logs and AWS Auth Manager logs.

Reverse Proxy Logs

Nginx
Apache HTTP server
Kubernetes ingress controllers

Identity Provider Logs

AWS IAM Identity Center
Okta
Azure AD
Other SAML IdP logs

Infrastructure Logs

Cloud load balancer logs
API gateway logs
Kubernetes audit logs

MITRE ATT&CK Mapping

Tactic	Technique
Initial Access	Exploit Public Facing Application (T1190)
Credential Access	Valid Accounts (T1078)
Defense Evasion	Modify Authentication Process
Persistence	Account Access Reuse

Mitigation

Immediate actions recommended:

Upgrade the Apache Airflow Amazon provider package
Implement strict host header validation
Restrict authentication endpoints behind trusted reverse proxies
Enable logging for authentication flows
Monitor SAML assertion reuse

Additional protective controls include:

enforcing allowed host configurations
blocking unexpected headers at reverse proxies
implementing strict SAML audience validation

Official Patch / Upgrade

The vulnerability has been resolved in:

Apache Airflow Amazon Provider version 9.22.0

Upgrade guidance and patch details are available at the official project repository:

https://github.com/apache/airflow/releases

Upgrading to the patched version ensures that the authentication origin is validated against the configured instance URL before a SAML response is accepted.

CVE-2026-25604: Critical SAML Authentication Flaw in AWS Auth Manager Allows Unauthorized Airflow Access