CVE-2026-26447 in Stomper
Summary
by MITRE • 08/26/2026
Stomper 5e2741e is vulnerable to Use-After-Free. When a single client repeatedly issues SUBSCRIBE commands for the same destination over one connection and then closes that connection, the broker performs incorrect cleanup of its internal subscription structures. This results in a heap use-after-free during StompClient destruction, causing the broker process to crash. An unauthenticated client can exploit this to reliably trigger a denial of service.
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Analysis
by VulDB Data Team • 08/26/2026
The vulnerability identified as CVE-5e2741e within the Stomper 5 application represents a critical memory management flaw classified under CWE-416, commonly known as Use-After-Free. This specific class of vulnerabilities occurs when program code references a pointer after it has been freed or deallocated by the system, leading to undefined behavior that can range from data corruption to arbitrary code execution and, in this instance, application crashes. The root cause lies within the broker's internal subscription management logic, specifically how it handles the lifecycle of client connections associated with persistent subscriptions over the STOMP protocol. When a single client establishes a connection and repeatedly issues SUBSCRIBE commands targeting the same destination, the broker allocates specific heap memory structures to track these active subscriptions.
The operational flaw manifests during the teardown phase of the connection. Upon receiving a close signal or when the client terminates the session, the broker initiates cleanup procedures for its internal subscription data structures. However, due to an incorrect implementation in this cleanup routine, references to the previously allocated subscription objects are not properly nullified or removed from active tracking lists before the memory is actually released. Consequently, if any subsequent operation attempts to access these subscription details during the destruction of the StompClient object, it interacts with freed heap memory. This race condition between reference removal and memory deallocation creates a reliable pathway for triggering a segmentation fault or similar crash mechanism within the broker process.
From an operational security perspective, this vulnerability poses a severe risk as it enables a remote denial-of-service attack without requiring any form of authentication. An unauthenticated attacker can exploit this flaw by simply establishing a connection to the vulnerable Stomper instance and executing the specific sequence of repeated subscriptions followed by immediate disconnection. This action reliably causes the broker process to crash, effectively disrupting service for all other users connected to that instance. The reliability of the trigger makes it particularly dangerous in production environments where availability is paramount, as an attacker can repeatedly bring down the messaging infrastructure with minimal effort and no prior credentials.
This incident aligns with several tactics within the MITRE ATT&CK framework, specifically relating to Resource Hijacking under the Impact tactic, where attackers aim to degrade or deny service by consuming resources or crashing services. Furthermore, it reflects common pitfalls in C/C++ memory management often seen in network daemons that handle high volumes of concurrent connections and dynamic state changes. To mitigate this vulnerability, developers must ensure strict adherence to safe pointer handling practices, such as setting pointers to null immediately after freeing the associated memory and implementing robust reference counting mechanisms or smart pointers to manage object lifecycles automatically. Additionally, incorporating static analysis tools and fuzzing techniques during the development lifecycle can help identify similar logic errors in subscription management before deployment. System administrators should also consider deploying network-level protections like rate limiting on connection establishment and subscription requests to mitigate the impact of such attacks until a patched version is available.