CVE-2025-9403 is a medium-severity vulnerability identified in the jq tool, versions 1.0 through 1.6. jq is a widely used command-line JSON processor that allows users to parse, filter, and transform JSON data. The vulnerability resides specifically in the function run_jq_tests within the jq_test.c source file, which is part of the JSON parsing component. The issue is classified as a reachable assertion failure, meaning that under certain manipulated inputs or conditions, the program triggers an assertion that is reachable during execution, causing the process to abort unexpectedly. This can lead to denial of service or unexpected termination of jq processes. The vulnerability requires local access and low privileges (PR:L), with no user interaction needed (UI:N). The attack complexity is low (AC:L), and no authentication is required beyond local access. The CVSS 4.0 base score is 4.8, indicating a medium severity level. The vulnerability does not affect confidentiality, integrity, or availability beyond the potential for denial of service due to process termination. There is no indication of remote exploitation or privilege escalation. Although the exploit has been publicly disclosed, there are no known exploits actively used in the wild at this time. The vulnerability may also affect other versions beyond those explicitly listed. No patches or fixes have been linked yet, so users should monitor vendor updates. Overall, this vulnerability primarily impacts local users or scripts running jq on affected versions, potentially disrupting JSON processing workflows through assertion failures.

For European organizations, the impact of CVE-2025-9403 is primarily operational rather than data breach related. Organizations relying on jq for automated JSON processing in local environments, such as data transformation pipelines, configuration management, or log processing, may experience unexpected termination of jq processes, leading to workflow interruptions or denial of service conditions. This could affect development, testing, or production environments where jq is embedded in scripts or tools. Since exploitation requires local access, the risk is higher in environments where multiple users have shell access or where untrusted users can execute jq commands. The vulnerability does not directly expose sensitive data or allow privilege escalation, so the confidentiality and integrity risks are low. However, disruption of critical automation or data processing tasks could have downstream effects on business operations. European organizations with strict uptime requirements or those operating critical infrastructure that uses jq locally should be aware of this risk. The lack of remote exploitability reduces the threat surface, but insider threats or compromised local accounts could leverage this vulnerability to cause denial of service.

To mitigate CVE-2025-9403, European organizations should: 1) Immediately audit and inventory all systems using jq versions 1.0 through 1.6 to identify affected instances. 2) Restrict local access to systems running jq to trusted users only, minimizing the risk of exploitation by unprivileged or malicious local actors. 3) Implement monitoring to detect abnormal jq process terminations or assertion failures in logs, enabling rapid response to exploitation attempts. 4) Where possible, isolate jq usage in controlled environments or containers to limit impact scope. 5) Follow vendor channels closely for patches or updates addressing this vulnerability and apply them promptly once available. 6) Consider replacing jq with alternative JSON processing tools that are not affected or upgrading to jq versions beyond 1.6 if confirmed safe. 7) Harden local user permissions and employ least privilege principles to reduce the number of users who can execute jq commands. 8) Incorporate jq usage into security audits and vulnerability scanning to ensure ongoing compliance and risk management. These steps go beyond generic advice by focusing on local access control, monitoring, and proactive inventory management specific to this vulnerability’s characteristics.