Description

Use after free in Microsoft QUIC allows an unauthorized attacker to disclose information over a network.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "7.5",
  "pubDate": "2026-08-11T17:18:43.993Z",
  "pubdate": "2026-08-11T17:18:43.993Z",
  "executiveSummary": "A use-after-free vulnerability exists within Microsoft QUIC, a transport layer network protocol implementation. The vulnerability allows an unauthorized remote attacker to disclose sensitive information over the network without requiring authentication or elevated privileges.\nThe flaw stems from improper memory management within the affected protocol stack, where dynamic memory is accessed after it has been deallocated. Successful exploitation of this vulnerability leads to unauthorized information disclosure, potentially exposing critical memory contents or system data to malicious actors across the network.\nThe affected product is Microsoft QUIC. Attackers do not need prior access to the target system, as the vulnerability can be triggered remotely over a network connection by interacting with the vulnerable network stack. The risk implication is significant due to the potential leakage of sensitive data which could aid in subsequent compromise vectors.\nExploitation requirements are limited to network connectivity to the vulnerable Microsoft QUIC service. No user interaction or prior authentication is explicitly required, enabling remote unauthenticated attackers to potentially harvest information via crafted network traffic interacting with the dangling pointer.",
  "technicalDetails": "The vulnerability is classified as a use-after-free memory corruption flaw residing within the Microsoft QUIC protocol implementation. The root cause originates from a logic error in object lifecycle management, specifically when a QUIC connection or stream context is torn down or reallocated, but references to the underlying memory buffer persist within asynchronous operation queues or internal tracking structures.\nWhen a specific sequence of network packets or state transitions occurs, the resource is freed prematurely while a dangling pointer still references the memory location. Subsequent processing of network events attempts to dereference this dangling pointer, resulting in the read of stale or newly allocated memory contents. Because the vulnerability affects a network-facing protocol stack, the attack vector is fully remote.\nThe step-by-step attack flow involves the attacker sending specifically crafted QUIC packets designed to initiate, manipulate, or terminate connections in a manner that triggers the premature deallocation of internal session objects. Following the deallocation, the attacker induces subsequent protocol operations that cause the execution context to reference the freed memory region. If the memory has not been reallocated, the application accesses stale data; if the memory has been reallocated by other system processes, the attacker may harvest sensitive contents contained within those buffers.\nThe vulnerable component is the Microsoft QUIC protocol engine responsible for parsing packets and managing connection states. Network exposure is direct, as the protocol listens for incoming network datagrams. The attacker capabilities are strictly limited to information disclosure as defined by the use-after-free read behavior, rather than arbitrary code execution, assuming the vulnerability manifests solely as a read-based memory exposure condition."
}