CVE-2025-38617 in Linux
Summary
by MITRE • 08/22/2025
In the Linux kernel, the following vulnerability has been resolved:
net/packet: fix a race in packet_set_ring() and packet_notifier()
When packet_set_ring() releases po->bind_lock, another thread can run packet_notifier() and process an NETDEV_UP event.
This race and the fix are both similar to that of commit 15fe076edea7 ("net/packet: fix a race in packet_bind() and packet_notifier()").
There too the packet_notifier NETDEV_UP event managed to run while a po->bind_lock critical section had to be temporarily released. And the fix was similarly to temporarily set po->num to zero to keep the socket unhooked until the lock is retaken.
The po->bind_lock in packet_set_ring and packet_notifier precede the introduction of git history.
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Analysis
by VulDB Data Team • 05/28/2026
The vulnerability identified as CVE-2025-38617 represents a race condition within the Linux kernel's packet socket implementation that specifically affects the interaction between packet_set_ring() and packet_notifier() functions. This issue occurs in the networking subsystem where the kernel's packet socket mechanism handles raw packet capture and transmission operations. The race condition manifests when packet_set_ring() releases the po->bind_lock, creating a window during which another thread can execute packet_notifier() and process a NETDEV_UP event, potentially leading to inconsistent socket state management and unpredictable behavior in network packet handling operations.
The technical flaw stems from the improper synchronization between the packet ring buffer configuration and network device notification processing within the packet socket framework. When packet_set_ring() temporarily releases the po->bind_lock to perform certain operations, it creates an opportunity for concurrent execution of packet_notifier() which processes network device up events. This timing window allows for inconsistent state management where the socket may be in an intermediate state between configuration changes and notification processing. The vulnerability is particularly concerning because it affects fundamental packet socket operations that are widely used for network monitoring, packet capture tools, and various network debugging utilities. The race condition is classified under CWE-362, which specifically addresses race conditions in concurrent programming, and aligns with ATT&CK technique T1046 for network service scanning and T1059 for command and scripting interpreter usage patterns that might exploit such inconsistencies.
The operational impact of this vulnerability extends across various network monitoring and security tools that rely on packet sockets for capturing and analyzing network traffic. Systems utilizing tools such as tcpdump, wireshark, or custom network monitoring applications may experience inconsistent packet capture behavior, potential data loss, or unexpected socket state transitions when multiple threads are simultaneously managing packet socket configurations and network device notifications. The vulnerability affects kernel versions where the packet socket subsystem operates, particularly impacting systems that frequently reconfigure packet sockets or experience rapid network device state changes. Attackers could potentially exploit this race condition to bypass network monitoring controls, manipulate packet capture operations, or cause denial of service conditions in network services that depend on reliable packet socket behavior. The fix implemented follows a well-established pattern similar to previous fixes in the kernel codebase, specifically referencing commit 15fe076edea7 that addressed similar issues in packet_bind() and packet_notifier() interactions.
The mitigation strategy for CVE-2025-38617 involves applying the kernel patch that implements the same synchronization mechanism used in the previous fix for packet_bind() race conditions. This approach temporarily sets po->num to zero during critical sections to prevent socket hooking until the lock is reacquired, ensuring that packet_notifier() cannot process network device events while packet_set_ring() is in the process of reconfiguring the socket. System administrators should prioritize updating their kernel versions to include this fix, particularly in environments running network monitoring tools or security applications that heavily utilize packet sockets. The fix maintains backward compatibility while providing the necessary synchronization guarantees to prevent the race condition from occurring. Organizations should also monitor their network monitoring infrastructure for any unusual packet capture behavior that might indicate exploitation attempts or the presence of unpatched systems within their network environment. Regular kernel updates and security auditing processes should include verification of packet socket functionality and proper synchronization mechanisms to prevent similar race conditions from affecting system stability and security posture.