CVE-2026-15713 in libsoup
Summary
by MITRE • 07/14/2026
A vulnerability was found in libsoup's HTTP/2 protocol implementation. The library fails to correctly release memory context blocks under specific stream termination conditions, such as when an HTTP/2 connection encounters window exhaustion or explicit stream resets. A remote, unauthenticated attacker acting as a malicious network peer can trick the connection engine into allocating stream states that are subsequently leaked during cleanup. Over a sustained period, this flaw allows the remote attacker to consume the system's heap allocations incrementally, triggering a denial of service (DoS) through an ultimate Out-of-Memory (OOM) application crash.
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Analysis
by VulDB Data Team • 07/15/2026
The vulnerability in libsoup's HTTP/2 implementation represents a critical memory management flaw that undermines the stability and security of applications relying on this library. This issue resides in the protocol handling layer where the library processes HTTP/2 connections, specifically affecting how it manages stream state cleanup during exceptional conditions. The flaw manifests when the HTTP/2 engine encounters scenarios such as window exhaustion or explicit stream resets, which are common occurrences in networked environments where bandwidth limitations and connection management policies are enforced. These conditions trigger a cascade of memory allocation decisions that ultimately result in resource leakage.
The technical execution of this vulnerability requires an attacker to act as a malicious network peer capable of establishing HTTP/2 connections with the target system. Through carefully crafted stream termination sequences, the attacker can manipulate the library's internal state management to allocate stream context blocks without proper cleanup. This memory leak occurs during the normal connection teardown process when the library attempts to release resources associated with terminated streams. The flaw is particularly insidious because it operates incrementally over time rather than causing immediate system failure, making detection more challenging and allowing sustained exploitation without obvious disruption to service availability.
The operational impact of this vulnerability extends beyond simple resource exhaustion, creating a pathway for sophisticated denial of service attacks that can be maintained over extended periods. Systems utilizing libsoup for HTTP/2 communication become increasingly vulnerable as the memory leak compounds, eventually leading to complete application crashes when heap allocations are exhausted. The incremental nature of the attack means that even modest network traffic volumes can accumulate sufficient memory pressure to trigger system instability. This vulnerability affects any application that depends on libsoup's HTTP/2 capabilities, including web servers, proxy systems, and client applications that handle HTTP/2 connections.
Security researchers categorize this flaw under CWE-401: Improper Release of Memory Before Removing Last Reference, which specifically addresses memory management issues where resources are not properly deallocated during normal cleanup operations. The vulnerability aligns with ATT&CK technique T1499.004: Endpoint Denial of Service - Resource Consumption, as it targets system resources through memory allocation manipulation rather than direct network disruption. Organizations should prioritize immediate patching of affected systems, implement monitoring for abnormal memory usage patterns, and consider network-level restrictions on HTTP/2 traffic to limit potential exploitation. Additionally, application developers should review their use of libsoup and consider alternative HTTP implementations or additional resource management layers to mitigate the risk during the patching process.
This vulnerability demonstrates the complexity of modern protocol implementations where seemingly minor memory management issues can cascade into significant security concerns. The flaw highlights the importance of rigorous testing for edge cases in network protocol handling, particularly under stress conditions that trigger resource exhaustion scenarios. The incremental nature of the attack also underscores the need for continuous system monitoring and anomaly detection capabilities to identify potential exploitation before complete system failure occurs, as traditional intrusion detection systems may not recognize this particular pattern of resource consumption as malicious activity.