CVE-2025-67899 identifies a vulnerability in the uriparser open-source URI parsing library, specifically affecting versions up to 0.9.9. The root cause is uncontrolled recursion within the ParseMustBeSegmentNzNc function when parsing URI segments containing numerous commas. This leads to unbounded recursion depth and excessive stack consumption, which can cause a stack overflow and crash the application, resulting in a denial of service (DoS). The vulnerability is classified under CWE-674 (Uncontrolled Recursion). The attack vector is local, meaning an attacker must have local access to the system to supply crafted input. The attack complexity is high, indicating that exploitation requires specific conditions or expertise. No privileges or user interaction are required, and the impact is limited to availability, with no impact on confidentiality or integrity. The CVSS v3.1 base score is 2.9, reflecting the low severity. No public exploits or patches are currently available, so mitigation relies on awareness and defensive coding practices. This vulnerability primarily affects applications or systems embedding uriparser for URI parsing, especially those processing untrusted input locally. Since uriparser is used in various software projects, the risk depends on deployment context. The vulnerability does not affect remote services directly, limiting its scope but still posing a risk for local DoS scenarios.

The primary impact of CVE-2025-67899 is a denial of service caused by stack overflow due to uncontrolled recursion in the uriparser library. For European organizations, this could disrupt local applications or embedded systems that rely on uriparser for URI parsing, particularly if they process untrusted or malformed input containing many commas. While the vulnerability does not compromise confidentiality or integrity, availability interruptions could affect critical systems, especially in sectors like manufacturing, telecommunications, or software development where uriparser might be embedded. The local attack vector and high complexity reduce the likelihood of widespread exploitation, but insider threats or compromised local users could trigger the issue. Organizations with automated URI processing pipelines or custom software using uriparser should be cautious. The lack of known exploits and patches means the threat is currently theoretical but should be addressed proactively to avoid future exploitation. Overall, the impact is low but non-negligible in environments where availability is critical.

To mitigate CVE-2025-67899, European organizations should: 1) Identify all software components and systems using uriparser, especially versions up to 0.9.9. 2) Implement strict input validation and sanitization to limit the size and complexity of URI inputs, particularly restricting the number of commas or segment delimiters processed locally. 3) Employ runtime protections such as stack size limits or recursion depth monitoring where possible to prevent stack overflow conditions. 4) Monitor vendor and open-source project updates for patches addressing this vulnerability and plan timely upgrades once available. 5) Conduct code reviews and static analysis on custom software integrating uriparser to detect unsafe recursion patterns. 6) Limit local access to systems processing untrusted URI inputs to reduce attack surface. 7) Consider alternative URI parsing libraries with better resilience to malformed input if feasible. These steps go beyond generic advice by focusing on local input controls, software inventory, and proactive monitoring tailored to the nature of this vulnerability.