In the Linux kernel, the following vulnerability has been resolved: ext4: fix BUG in ext4_mb_new_inode_pa() due to overflow. When we calculate the end position of ext4_free_extent, this position may be exactly where ext4_lblk_t (i.e. uint) overflows. For example, if ac_g_ex.fe_logical is 4294965248 and ac_orig_goal_len is 2048, then the computed end is 0x100000000, which is 0. If ac->ac_o_ex.fe_logical is not the first case of adjusting the best extent, that is, new_bex_end > 0, the following BUG_ON will be triggered.
This vulnerability allows attackers to create conditions that lead to a kernel bug, which can impact the stability of systems using the ext4 file system. The overflow in the calculation could lead to unexpected behaviors, potentially affecting data integrity and system reliability.
The urgency for defenders is moderate, as the vulnerability has been marked as deferred and there are currently no known exploits. However, organizations should stay informed about this vulnerability and monitor for updates.
The vulnerability is classified as having an unknown severity level and has a low exploitability rating. Organizations should assess their use of the Linux kernel and apply any available updates to mitigate potential risks.
Organizations should prioritize patching immediately if a fix becomes available, given the potential impacts of this vulnerability.
Vulnerability Details
In the Linux kernel, the following vulnerability has been resolved: ext4: fix BUG in ext4_mb_new_inode_pa() due to overflow.
The vulnerability details can be traced back to an overflow in the calculation of the end position of ext4_free_extent. This occurs when the logical block number exceeds certain thresholds, resulting in invalid operations that can crash the kernel.
Publication Date: December 24, 2025 | Last Modified: April 15, 2026
Technical Analysis
The root cause of this vulnerability is related to the incorrect handling of logical block numbers during memory allocation in the ext4 file system. The attack vector is local, as it requires access to the filesystem to exploit the vulnerability.
With a low attack complexity, this vulnerability has low privileges required for exploitation, and no user interaction is necessary. The impacts on confidentiality, integrity, and availability are currently assessed as low due to the lack of known exploits.
Risk & Impact Analysis
Risk to organizations includes potential system crashes and data corruption. Given the deferred status of this vulnerability and lack of active exploitation, organizations should monitor the situation closely.
Organizations should assess the impact of this vulnerability on their systems and prioritize monitoring for updates from the Linux kernel community regarding patches and fixes.
Due to the low EPSS score, the likelihood of exploitation in the wild appears low at this time. However, proactive risk management strategies should be considered.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
All versions prior to vendor patch.
Mitigation & Remediation
Organizations should monitor for patches related to this vulnerability. If a fix becomes available, it should be applied immediately. In the meantime, implementing strong access controls and monitoring filesystem activities can help mitigate potential risks.
For further information on penetration testing and security assessments, organizations can utilize our penetration testing services to validate their security posture.
Detection Guidance
Organizations should monitor logs for any unusual filesystem behavior and kernel errors related to memory allocation or ext4 operations. Anomalies in disk usage patterns may also indicate attempts to exploit this vulnerability.
AppSecure Threat Intelligence Insight
This vulnerability highlights the importance of maintaining up-to-date systems and understanding potential impacts associated with file system overflows. Security teams should consider implementing robust monitoring solutions to detect any signs of exploitation in real-time.
For more information on best practices in security, teams can refer to our penetration testing methodology article.
Additionally, understanding the trends in vulnerabilities and attack patterns can further enhance an organization's security posture. Our blog on the 2025 vulnerability exposure trends provides valuable insights.
Lastly, organizations should consider engaging in red teaming exercises to stress-test their defenses against potential exploits, as detailed in our red teaming guide to better prepare for real-world attacks.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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