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CVE-2025-38527


In the Linux kernel, the following vulnerability has been resolved: smb: client: fix use-after-free in cifs_oplock_break A race condition can occur in cifs_oplock_break() leading to a use-after-free of the cinode structure when unmounting: cifs_oplock_break() _cifsFileInfo_put(cfile) cifsFileInfo_put_final() cifs_sb_deactive() [last ref, start releasing sb] kill_sb() kill_anon_super() generic_shutdown_super() evict_inodes() dispose_list() evict() destroy_inode() call_rcu(&inode->i_rcu, i_callback) spin_lock(&cinode->open_file_lock) <- OK [later] i_callback() cifs_free_inode() kmem_cache_free(cinode) spin_unlock(&cinode->open_file_lock) <- UAF cifs_done_oplock_break(cinode) <- UAF The issue occurs when umount has already released its reference to the superblock. When _cifsFileInfo_put() calls cifs_sb_deactive(), this releases the last reference, triggering the immediate cleanup of all inodes under RCU. However, cifs_oplock_break() continues to access the cinode after this point, resulting in use-after-free. Fix this by holding an extra reference to the superblock during the entire oplock break operation. This ensures that the superblock and its inodes remain valid until the oplock break completes.


Security Impact Summary

This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.8, requiring local system access to exploit with relatively low complexity without requiring user interaction requiring only low-level privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 2 products from linux, from debian organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2025, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.


Published

2025-08-16T12:15:28.183

Last Modified

2026-01-07T17:38:48.213

Status

Analyzed

Source

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Severity

CVSSv3.1: 7.8 (HIGH)

Weaknesses
  • Type: Primary
    CWE-416

Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Operating System linux linux_kernel < 3.17 Yes
Operating System linux linux_kernel < 4.10 Yes
Operating System linux linux_kernel < 4.15 Yes
Operating System linux linux_kernel < 4.20 Yes
Operating System linux linux_kernel < 5.1 Yes
Operating System linux linux_kernel < 5.15.190 Yes
Operating System linux linux_kernel < 6.1.147 Yes
Operating System linux linux_kernel < 6.6.100 Yes
Operating System linux linux_kernel < 6.12.40 Yes
Operating System linux linux_kernel < 6.15.8 Yes
Operating System linux linux_kernel 5.1 Yes
Operating System linux linux_kernel 5.1 Yes
Operating System linux linux_kernel 5.1 Yes
Operating System linux linux_kernel 6.16 Yes
Operating System linux linux_kernel 6.16 Yes
Operating System linux linux_kernel 6.16 Yes
Operating System linux linux_kernel 6.16 Yes
Operating System linux linux_kernel 6.16 Yes
Operating System linux linux_kernel 6.16 Yes
Operating System debian debian_linux 11.0 Yes

References

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For linux's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.