CVE-2026-64077 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
netfilter: ebtables: move to two-stage removal scheme
Like previous patches for x_tables, follow same pattern in ebtables. We can't reuse xt helpers: ebt_table struct layout is incompatible.
table->ops assignment is now done while still holding the ebt mutex to make sure we never expose partially-filled table struct.
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Analysis
by VulDB Data Team • 07/19/2026
The vulnerability addressed in this linux kernel patch relates to a race condition within the netfilter ebtables subsystem that could potentially lead to system instability or privilege escalation. This issue specifically affects the ebt_table structure management during the removal process, where improper synchronization could allow concurrent access to partially initialized data structures. The problem stems from the lack of proper sequential ordering in the table removal mechanism, creating opportunities for malicious actors to exploit timing windows during kernel operation.
This vulnerability represents a classic race condition scenario that aligns with CWE-362 - Concurrent Execution Using Shared Resource with Unprotected Race Condition, and can be mapped to ATT&CK technique T1068 - Exploitation for Privilege Escalation. The core technical flaw occurs when the ebtables subsystem attempts to remove table structures without proper synchronization mechanisms, allowing multiple threads or processes to access the same data structure during its destruction phase. Unlike traditional x_tables implementations that already employed a two-stage removal scheme, ebtables lacked this critical protection mechanism.
The operational impact of this vulnerability extends beyond simple system instability, as it could potentially enable local privilege escalation attacks where malicious code exploits the race condition to gain elevated privileges within the kernel space. The issue becomes particularly concerning in environments where ebtables is actively used for network filtering and packet manipulation, as attackers could leverage this weakness to compromise system integrity. The patch implementation addresses this by adopting a two-stage removal approach similar to previous x_tables fixes, ensuring that table operations are properly sequenced.
The mitigation strategy implemented in this fix involves modifying the table removal process to maintain exclusive access to the ebt_mutex throughout the entire removal sequence, preventing any partial exposure of the ebt_table structure. This approach ensures that the table->ops assignment occurs while still holding the mutex, thereby guaranteeing that no other thread can access a partially constructed or destructed table structure. The solution specifically avoids reusing xt helpers due to incompatible struct layouts between the two subsystems, maintaining architectural integrity while providing the necessary synchronization guarantees. This pattern of staged removal has proven effective in similar kernel subsystems and follows established best practices for concurrent kernel data structure management.
The fix demonstrates proper adherence to kernel security principles by implementing proper locking mechanisms and sequential operations that prevent race conditions during critical data structure modifications. The approach taken aligns with kernel development standards that emphasize the importance of maintaining data structure integrity throughout all phases of object lifecycle management, particularly in multi-threaded environments where concurrent access patterns can lead to unpredictable behavior and security vulnerabilities.