CVE-2025-21721 Vulnerability Analysis & Exploit Details

CVE-2025-21721
Vulnerability Scoring

Analysis In Progress
Analysis In Progress

Attack Complexity Details

  • Attack Complexity:
    Attack Complexity Analysis In Progress
  • Attack Vector:
    Attack Vector Under Analysis
  • Privileges Required: None
    No authentication is required for exploitation.
  • Scope:
    Impact is confined to the initially vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2025-21721 Details

Status: Awaiting Analysis

Last updated: 🕐 13 Mar 2025, 13:15 UTC
Originally published on: 🕑 27 Feb 2025, 02:15 UTC

Time between publication and last update: 14 days

CVSS Release:

CVE-2025-21721 Vulnerability Summary

CVE-2025-21721: In the Linux kernel, the following vulnerability has been resolved: nilfs2: handle errors that nilfs_prepare_chunk() may return Patch series "nilfs2: fix issues with rename operations". This series fixes BUG_ON check failures reported by syzbot around rename operations, and a minor behavioral issue where the mtime of a child directory changes when it is renamed instead of moved. This patch (of 2): The directory manipulation routines nilfs_set_link() and nilfs_delete_entry() rewrite the directory entry in the folio/page previously read by nilfs_find_entry(), so error handling is omitted on the assumption that nilfs_prepare_chunk(), which prepares the buffer for rewriting, will always succeed for these. And if an error is returned, it triggers the legacy BUG_ON() checks in each routine. This assumption is wrong, as proven by syzbot: the buffer layer called by nilfs_prepare_chunk() may call nilfs_get_block() if necessary, which may fail due to metadata corruption or other reasons. This has been there all along, but improved sanity checks and error handling may have made it more reproducible in fuzzing tests. Fix this issue by adding missing error paths in nilfs_set_link(), nilfs_delete_entry(), and their caller nilfs_rename().

Assessing the Risk of CVE-2025-21721

Access Complexity Graph

The exploitability of CVE-2025-21721 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2025-21721

No exploitability data is available for CVE-2025-21721.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2025-21721, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2025-21721, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2025-21721 does not compromise confidentiality.
  • Integrity: None
    CVE-2025-21721 does not impact data integrity.
  • Availability: None
    CVE-2025-21721 does not affect system availability.

Exploit Prediction Scoring System (EPSS)

The EPSS score estimates the probability that this vulnerability will be exploited in the near future.

EPSS Score: 0.044% (probability of exploit)

EPSS Percentile: 15.85% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 84.15% of others.

CVE-2025-21721 References

External References

CWE Common Weakness Enumeration

Unknown

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