CVE-2025-61785 is a vulnerability identified in the Deno runtime environment, which supports JavaScript, TypeScript, and WebAssembly execution. The issue arises from incorrect privilege assignment related to file timestamp modification APIs. Specifically, the methods Deno.FsFile.prototype.utime and utimeSync allow changing the access time (atime) and modification time (mtime) of a file stream resource even when the file is opened with read-only permissions and the runtime is executed with the --deny-write=./ flag, which is intended to prevent any write operations. This bypass occurs because these methods do not enforce the permission model correctly, unlike other similar APIs such as Deno.utime and Deno.utimeSync, which require explicit allow-write permissions. The vulnerability affects Deno versions >= 2.3.0 and < 2.5.3, and versions prior to 2.2.15. The flaw allows an attacker or script with limited privileges to alter file timestamps without write permissions, potentially undermining file integrity and audit mechanisms that rely on accurate metadata. However, the vulnerability does not allow modification of file contents or deletion, limiting its impact. The issue was publicly disclosed on October 8, 2025, with no known exploits in the wild. The fix was implemented in versions 2.5.3 and 2.2.15 by enforcing proper permission checks on these APIs. The CVSS v3.0 score is 3.3, reflecting low severity due to local attack vector, low impact on integrity, and no impact on confidentiality or availability.

For European organizations, the primary impact of CVE-2025-61785 lies in the potential manipulation of file metadata, specifically access and modification timestamps, without proper write permissions. This can undermine the integrity of file audit trails, compliance logs, and forensic investigations that rely on accurate timestamps to detect unauthorized changes or access patterns. Organizations using Deno in development, continuous integration pipelines, or production environments where file integrity and auditability are critical may face challenges in trustworthiness of file metadata. While the vulnerability does not permit direct modification of file content or deletion, altering timestamps could be leveraged in sophisticated attack scenarios to obfuscate malicious activity or evade detection. The low CVSS score and lack of known exploits suggest limited immediate risk, but the vulnerability could be exploited in targeted attacks where timestamp manipulation aids in stealth. European sectors with stringent compliance requirements, such as finance, healthcare, and government, may be particularly sensitive to such integrity issues. Additionally, organizations relying on automated monitoring tools that track file changes might experience false negatives or misinterpretations if timestamps are tampered with.

1. Upgrade all Deno runtime environments to version 2.5.3 or later, or 2.2.15 or later, where the vulnerability is patched. 2. Audit existing scripts and applications that use Deno.FsFile.prototype.utime and utimeSync APIs to identify and remediate any unauthorized or unnecessary usage. 3. Implement strict code review and permission management policies to ensure scripts do not run with excessive privileges, especially avoiding unnecessary file system access. 4. Enhance monitoring and alerting on file metadata changes, correlating timestamp modifications with other system events to detect suspicious activity. 5. Use file integrity monitoring solutions that verify not only file contents but also metadata consistency to detect unauthorized timestamp changes. 6. Educate developers and DevOps teams about the importance of permission enforcement in Deno and encourage adoption of secure coding practices. 7. Consider isolating or sandboxing Deno runtime environments where possible to limit the scope of potential misuse. 8. Maintain an inventory of Deno versions deployed across the organization to ensure timely patching and vulnerability management.