CVE-2026-64371 in Linux
Summary
by MITRE • 07/25/2026
In the Linux kernel, the following vulnerability has been resolved:
proc: protect ptrace_may_access() with exec_update_lock (part 1)
Fix the easy cases where procfs currently calls ptrace_may_access() without exec_update_lock protection, where the fix is to simply add the extra lock or use mm_access():
- do_task_stat(): grab exec_update_lock - proc_pid_wchan(): grab exec_update_lock - proc_map_files_lookup(): use mm_access() instead of get_task_mm() - proc_map_files_readdir(): use mm_access() instead of get_task_mm() - proc_ns_get_link(): grab exec_update_lock - proc_ns_readlink(): grab exec_update_lock
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Analysis
by VulDB Data Team • 07/25/2026
The vulnerability addressed in this linux kernel patch relates to insufficient synchronization mechanisms when accessing process information through the proc filesystem. This issue specifically impacts the ptrace_may_access() function which is responsible for determining whether a process can access another process's memory or attributes. The problem arises from cases where procfs operations call ptrace_may_access() without proper locking around the execution update lock, creating potential race conditions that could allow unauthorized access to process information.
The technical flaw stems from improper coordination between the proc filesystem and kernel memory management subsystems during process attribute access operations. When procfs routines access process information through ptrace_may_access(), they must ensure proper synchronization with the execution update lock to prevent concurrent modifications to process memory mappings or execution states. Without this protection, malicious processes could potentially exploit timing windows where process memory states are temporarily inconsistent, leading to privilege escalation or information disclosure vulnerabilities.
Several specific procfs operations were identified as requiring immediate remediation including do_task_stat() which now properly acquires the exec_update_lock before calling ptrace_may_access(), and proc_pid_wchan() which implements the same protective measure. Additionally, the patch addresses proc_map_files_lookup() and proc_map_files_readdir() by replacing get_task_mm() calls with mm_access() which provides proper locking semantics. The proc_ns_get_link() and proc_ns_readlink() functions also received similar protection through exec_update_lock acquisition.
The operational impact of this vulnerability could be significant for systems running vulnerable kernel versions, as it creates potential attack vectors for privilege escalation attacks. An attacker could exploit the race conditions to gain unauthorized access to process memory mappings or execution contexts, potentially leading to information disclosure or system compromise. The fix ensures that all procfs operations accessing ptrace_may_access() properly synchronize with the execution update lock, preventing concurrent access patterns that could lead to inconsistent process state views.
This vulnerability aligns with common weakness enumerations such as CWE-362, which describes race conditions in concurrent programming, and CWE-284, which covers improper access control mechanisms. The mitigation strategy follows established security practices by implementing proper locking mechanisms around critical sections of code that handle inter-process memory access. The solution also reflects ATT&CK technique T1059, which involves using system calls to gain access to process information, but in this case the fix prevents unauthorized access through proper synchronization rather than bypassing controls.
The implementation changes demonstrate good security engineering practices by ensuring all code paths that interact with ptrace_may_access() maintain consistent locking behavior. The use of mm_access() instead of get_task_mm() in specific cases provides more appropriate access control semantics while maintaining performance characteristics. These modifications align with kernel security best practices and help maintain the integrity of process isolation mechanisms that are fundamental to operating system security.
The patch addresses a critical area of kernel security by ensuring proper synchronization between process filesystem operations and memory management subsystems. This vulnerability represents a classic example of how seemingly simple access control functions can become attack vectors when proper concurrency controls are missing from code paths that handle sensitive process information, making the fix essential for maintaining overall system security posture.
The remediation approach taken in this patch follows established kernel development practices for addressing race conditions in memory management operations. By requiring explicit locking around ptrace_may_access() calls, the kernel maintains consistent behavior across all procfs operations that need to examine process attributes. This protective measure prevents potential privilege escalation scenarios where an attacker could manipulate process state during the window between when memory mappings are accessed and when they are validated, thus maintaining proper access controls throughout the system's operation.