CVE-2026-116476 in a2a-dotnet
Summary
by MITRE • 10/26/2026
A weakness has been identified in a2aproject a2a-dotnet up to 1.0.0-preview3. The affected element is the function TaskProjection.ApplyStatus of the component TaskProjection. Executing a manipulation can lead to race condition. The attack may be performed from remote. The pull request to fix this issue awaits acceptance.
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Analysis
by VulDB Data Team • 10/26/2026
The identified vulnerability resides within the a2a-dotnet library, specifically affecting versions up through 1.0.0-preview3 in the TaskProjection component. This software framework is designed to manage asynchronous task projections and state management for distributed systems or event-driven architectures. The core issue centers on the ApplyStatus function, which is responsible for updating the current status of a projected task based on incoming events or commands. In concurrent environments where multiple threads may attempt to modify the same task projection simultaneously, this specific implementation lacks adequate synchronization mechanisms to ensure atomicity during state transitions. This absence of proper locking or optimistic concurrency control creates a classic race condition scenario that can compromise data integrity and system reliability.
From a technical perspective, the flaw allows for non-deterministic behavior when multiple requests attempt to apply status updates concurrently. Without strict mutual exclusion or version checking mechanisms such as Compare-And-Swap operations, two threads might read the same initial state of a task projection, both decide on an update based on that stale data, and then write their respective changes back sequentially. The second write overwrites the first, effectively losing one of the status updates. This type of error is categorized under CWE-362, which defines concurrent execution using shared resources with improper synchronization. In complex distributed systems relying on a2a-dotnet for state consistency, such race conditions can lead to tasks being stuck in incorrect states, duplicate processing of events, or loss of critical operational data that depends on accurate status tracking.
The operational impact of this vulnerability is significant because it enables remote attackers to exploit the timing window between reading and writing task statuses. Since the attack vector is network-based, an adversary who can send concurrent requests to a service utilizing this library could manipulate the outcome of asynchronous operations. This might result in financial discrepancies if the system handles transactions, security breaches if access control states are affected by race conditions, or general denial of service through corrupted internal state that prevents further processing. The ability to perform these manipulations remotely increases the severity as it does not require local access or authentication bypass beyond what is already exposed via the network interface handling task projections.
This vulnerability aligns with MITRE ATT&CK technique T1059, specifically Command and Scripting Interpreter scenarios where race conditions are leveraged to escalate privileges or alter system behavior, although in this context it primarily affects data integrity rather than direct command execution. The lack of atomicity in state updates is a common pitfall in high-throughput asynchronous applications, often stemming from an over-reliance on simple property setters without underlying thread-safe abstractions. Developers using the library must be aware that even if individual operations appear safe, their composition within concurrent workflows can introduce subtle but critical flaws.
Mitigation strategies should focus on implementing robust concurrency controls within the TaskProjection component. Ideally, this involves replacing direct state assignments with database-level optimistic locking mechanisms or application-level mutex locks to ensure that status updates are applied atomically. If using a persistent store for projections, version columns or timestamp checks can prevent stale writes from overwriting newer data. Until an official patch is released and accepted into the main branch, users of versions up to 1.0.0-preview3 should consider isolating affected services in read-only modes if possible, limiting concurrent access through rate limiting at the API gateway level, or implementing custom synchronization wrappers around calls to ApplyStatus. Monitoring for anomalies in task status transitions can also help detect exploitation attempts in real-time while awaiting the upstream fix.