CVE-2025-48935 is a medium-severity vulnerability affecting the Deno runtime, a secure JavaScript, TypeScript, and WebAssembly runtime environment. The vulnerability exists in versions 2.2.0 up to but not including 2.2.5. It involves an incorrect authorization flaw (CWE-863) that allows an attacker to bypass Deno's permission model specifically related to read/write database permissions. The issue arises from the ability to use the SQL `ATTACH DATABASE` statement to circumvent the permission checks that Deno enforces to restrict access to file system resources. This means that an attacker or malicious code running within Deno could potentially access or modify database files without having the appropriate permissions explicitly granted. The flaw does not require any privileges, user interaction, or authentication, and can be exploited remotely if the attacker can execute code within the Deno runtime environment. The vulnerability was patched in version 2.2.5 of Deno, which properly enforces permission checks to prevent unauthorized database attachment operations. The CVSS 4.0 base score is 5.5, reflecting a medium severity with network attack vector, low attack complexity, no privileges or user interaction required, and limited impact on integrity (partial). No known exploits are currently reported in the wild. This vulnerability highlights a critical aspect of Deno's security model, where permission enforcement is fundamental to its design, and bypassing it could lead to unauthorized data access or modification within applications using Deno for server-side or scripting purposes.

For European organizations, the impact of this vulnerability depends largely on the extent to which Deno is used in their technology stacks, particularly in environments handling sensitive data or critical applications. Organizations using Deno to run backend services, APIs, or automation scripts that interact with databases could face unauthorized data access or modification risks if they run vulnerable versions. This could lead to data integrity issues, potential data leakage, or unauthorized data manipulation. Since Deno is often chosen for its security model, this vulnerability undermines that trust and could expose organizations to compliance risks, especially under GDPR where unauthorized data access must be prevented. The vulnerability could also be leveraged as part of a larger attack chain to escalate privileges or move laterally within a network if an attacker gains initial code execution. However, the medium severity and lack of known exploits suggest the immediate risk is moderate, but organizations should prioritize patching to maintain a strong security posture.

European organizations should take the following specific actions to mitigate this vulnerability: 1) Identify all instances of Deno runtime in use, including development, testing, and production environments, with a focus on versions between 2.2.0 and 2.2.4 inclusive. 2) Upgrade all affected Deno installations to version 2.2.5 or later, which contains the patch that enforces proper permission checks on database attachment operations. 3) Review and audit permission configurations in Deno applications to ensure the principle of least privilege is applied, minimizing granted read/write permissions to only necessary resources. 4) Implement runtime monitoring and logging for database access operations within Deno applications to detect anomalous or unauthorized attachment attempts. 5) For environments where immediate patching is not feasible, consider restricting network access to Deno services and applying application-layer controls to limit execution of untrusted code. 6) Educate developers and DevOps teams about the importance of applying security patches promptly and verifying permission enforcement in Deno-based applications. 7) Incorporate this vulnerability into vulnerability management and incident response plans to ensure rapid detection and remediation if exploitation attempts occur.