CVE-2023-53662 in Linux
Summary
by MITRE • 10/07/2025
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix memory leaks in ext4_fname_{setup_filename,prepare_lookup}
If the filename casefolding fails, we'll be leaking memory from the fscrypt_name struct, namely from the 'crypto_buf.name' member.
Make sure we free it in the error path on both ext4_fname_setup_filename() and ext4_fname_prepare_lookup() functions.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 03/23/2026
The vulnerability CVE-2023-53662 represents a memory leak issue within the Linux kernel's ext4 filesystem implementation that specifically affects the handling of filename casefolding operations. This flaw exists in the ext4 filesystem driver where the kernel fails to properly release allocated memory resources when casefolding operations encounter errors during filename processing. The issue manifests in two critical functions within the filesystem codebase: ext4_fname_setup_filename and ext4_fname_prepare_lookup, which are responsible for preparing filename structures for casefolding operations. When these functions encounter failure conditions during casefolding, they neglect to free the crypto_buf.name member of the fscrypt_name struct, resulting in gradual memory consumption that can lead to system instability and resource exhaustion over time.
The technical root cause of this vulnerability stems from improper error handling within the ext4 filesystem implementation where memory allocation occurs for cryptographic buffer structures but fails to be properly deallocated when error conditions are encountered. The fscrypt_name structure contains a crypto_buf member that holds name data required for cryptographic operations during casefolding, and when these operations fail, the crypto_buf.name field remains allocated in memory. This memory leak pattern directly violates standard memory management practices and represents a classic case of resource leak vulnerability that can be categorized under CWE-404, which specifically addresses "Improper Resource Release or Recovery." The issue becomes particularly problematic in high-usage environments where extensive filename operations occur, as the cumulative effect of these leaks can significantly impact system performance and available memory resources.
The operational impact of CVE-2023-53662 extends beyond simple memory consumption, as it can contribute to system degradation and potential denial of service conditions in environments with heavy filesystem usage. When the memory leaks accumulate over time, they can lead to reduced system responsiveness, increased memory pressure, and potentially cause the system to become unresponsive or crash under extreme conditions. This vulnerability affects systems running Linux kernel versions that include the affected ext4 filesystem code, particularly those implementing casefolding functionality for filename handling. The issue is particularly concerning in enterprise environments where filesystem performance and reliability are critical, as memory leaks can compound over time and may not be immediately apparent to system administrators. The vulnerability's impact is amplified in systems that frequently perform casefolding operations, which are common in modern filesystem implementations that support Unicode normalization and case-insensitive file access patterns.
Mitigation strategies for CVE-2023-53662 primarily involve applying the kernel patches that address the improper memory release in the ext4 filesystem code. System administrators should prioritize updating their Linux kernel installations to versions that include the fix for this vulnerability, which specifically ensures that the crypto_buf.name member is properly freed in error paths within both ext4_fname_setup_filename and ext4_fname_prepare_lookup functions. The fix implements proper error handling that guarantees memory cleanup regardless of whether casefolding operations succeed or fail. Organizations should also implement monitoring solutions to track memory usage patterns and identify potential memory leak impacts before they escalate into system stability issues. Security teams should consider this vulnerability as part of their broader kernel security maintenance programs, particularly in environments where filesystem performance and resource management are critical. The remediation process should include thorough testing of kernel updates in staging environments to ensure compatibility and prevent regressions in filesystem functionality while addressing the memory leak issue through proper implementation of the fix that aligns with established security practices and system reliability standards.