Summary
A server-side request forgery vulnerability in a2a-rs allows a remote attacker to influence the TaskPushNotificationConfig used by the HttpPushSender component. If attacker-controlled destination values are accepted, the server may be induced to send requests to unintended internal or external resources.
A server-side request forgery vulnerability in a2a-rs allows a remote attacker to influence the TaskPushNotificationConfig used by the HttpPushSender component. If attacker-controlled destination values are accepted, the server may be induced to send requests to unintended internal or external resources.
Affected context
The issue occurs in deployments using the a2a-rs Push Notification Handler and its HttpPushSender implementation. Risk depends on whether remote or otherwise untrusted input can influence TaskPushNotificationConfig values and whether the server has network access to sensitive internal services or metadata endpoints.
The issue occurs in deployments using the a2a-rs Push Notification Handler and its HttpPushSender implementation. Risk depends on whether remote or otherwise untrusted input can influence TaskPushNotificationConfig values and whether the server has network access to sensitive internal services or metadata endpoints.
Exploit preconditions
- Attack surface: The remotely reachable push notification handling functionality
- Required access: Ability to submit or influence a TaskPushNotificationConfig value through an exposed application interface
- Trigger point: Processing the configured destination when HttpPushSender performs an outbound HTTP request
- Why exploitation is possible: Destination input is insufficiently restricted, allowing the server to make requests to attacker-selected or otherwise unintended locations
- Attack surface: The remotely reachable push notification handling functionality
- Required access: Ability to submit or influence a TaskPushNotificationConfig value through an exposed application interface
- Trigger point: Processing the configured destination when HttpPushSender performs an outbound HTTP request
- Why exploitation is possible: Destination input is insufficiently restricted, allowing the server to make requests to attacker-selected or otherwise unintended locations
Why this happens
The vulnerability results from treating a request destination supplied through TaskPushNotificationConfig as trusted without adequately constraining where the server may connect.
This maps to CWE-918: Server-Side Request Forgery, in which application-controlled network functionality can be redirected by an attacker toward internal, local, or restricted resources. The insecure pattern is accepting externally influenced URLs or endpoints without robust destination validation, network segmentation, and request policy enforcement.
The vulnerability results from treating a request destination supplied through TaskPushNotificationConfig as trusted without adequately constraining where the server may connect.
This maps to CWE-918: Server-Side Request Forgery, in which application-controlled network functionality can be redirected by an attacker toward internal, local, or restricted resources. The insecure pattern is accepting externally influenced URLs or endpoints without robust destination validation, network segmentation, and request policy enforcement.
Potential impact
- An attacker may cause requests to internal services that are not directly internet-accessible
- Sensitive service responses or metadata may be exposed
- The server could be used to reach administrative or cloud control-plane endpoints
- Internal network reconnaissance may be performed through request behavior
- Downstream systems could receive unintended requests from a trusted server
- An attacker may cause requests to internal services that are not directly internet-accessible
- Sensitive service responses or metadata may be exposed
- The server could be used to reach administrative or cloud control-plane endpoints
- Internal network reconnaissance may be performed through request behavior
- Downstream systems could receive unintended requests from a trusted server
General mitigation guidance
Mitigation generally focuses on reducing trust in configured destinations and enforcing outbound request policies.
Common defensive patterns include:
- Allowing requests only to explicitly approved hosts, schemes, ports, and paths
- Resolving hostnames and validating resulting addresses against private, loopback, link-local, and reserved ranges
- Rechecking destinations after redirects and preventing unsafe redirect behavior
- Applying egress filtering and network segmentation at the runtime or platform layer
- Using dedicated low-privilege network identities for outbound requests
- Avoiding exposure of sensitive metadata or administrative endpoints to application runtimes
Mitigation generally focuses on reducing trust in configured destinations and enforcing outbound request policies.
Common defensive patterns include:
- Allowing requests only to explicitly approved hosts, schemes, ports, and paths
- Resolving hostnames and validating resulting addresses against private, loopback, link-local, and reserved ranges
- Rechecking destinations after redirects and preventing unsafe redirect behavior
- Applying egress filtering and network segmentation at the runtime or platform layer
- Using dedicated low-privilege network identities for outbound requests
- Avoiding exposure of sensitive metadata or administrative endpoints to application runtimes
How teams detect issues like this
Organizations commonly detect SSRF risks through:
- Static analysis rules for HTTP clients that consume user-controlled or configuration-controlled URLs
- Code review checks for missing URL allowlists, redirect controls, and private-address validation
- Dynamic testing with controlled callback endpoints and requests targeting blocked address ranges
- Egress monitoring for unexpected connections to internal, loopback, link-local, or cloud metadata addresses
- Policy enforcement that restricts outbound destinations from application workloads
Automated security review tools can help identify tainted URL flows and missing network-boundary checks.
Organizations commonly detect SSRF risks through:
- Static analysis rules for HTTP clients that consume user-controlled or configuration-controlled URLs
- Code review checks for missing URL allowlists, redirect controls, and private-address validation
- Dynamic testing with controlled callback endpoints and requests targeting blocked address ranges
- Egress monitoring for unexpected connections to internal, loopback, link-local, or cloud metadata addresses
- Policy enforcement that restricts outbound destinations from application workloads
Automated security review tools can help identify tainted URL flows and missing network-boundary checks.
Sources
| Source | Link |
|---|---|
| github. | github.com/ |
| github. | github.com/ |
| github. | github.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
| vuldb. | vuldb.com/ |
