CVE-2025-5892 is a vulnerability identified in RocketChat versions 7.6.0 and 7.6.1, specifically within the parseMessage function located in the /apps/meteor/app/irc/server/servers/RFC2813/parseMessage.js file. The vulnerability arises due to inefficient regular expression complexity when processing the 'line' argument. This inefficiency can be exploited remotely by an attacker who crafts malicious input to trigger excessive backtracking or other costly regex operations, leading to a denial-of-service (DoS) condition. The vulnerability does not require user interaction or authentication, making it remotely exploitable over the network. The CVSS 4.0 base score is 5.3 (medium severity), reflecting that the attack vector is network-based with low attack complexity and no privileges or user interaction required. The impact primarily affects availability, as the inefficient regex can cause the server process to consume excessive CPU resources, potentially leading to service degradation or outage. No known exploits are currently observed in the wild, but public disclosure of the exploit details increases the risk of exploitation. The vulnerability is classified as problematic, indicating it is a notable but not critical flaw. No official patches or fixes are currently linked, so mitigation may require workarounds or updates from the vendor. The root cause is the use of a vulnerable regex pattern in message parsing, which can be manipulated to cause performance issues.

For European organizations using RocketChat versions 7.6.0 or 7.6.1, this vulnerability poses a risk of service disruption due to denial-of-service attacks. RocketChat is widely used for internal communication and collaboration, so an outage could impact business continuity, employee productivity, and communication reliability. Organizations in sectors with high dependence on real-time messaging, such as finance, healthcare, and government, could experience operational delays or interruptions. Although the vulnerability does not lead to data breach or integrity compromise, the availability impact can indirectly affect confidentiality if communication channels are disrupted. The remote and unauthenticated nature of the exploit increases the attack surface, especially for publicly accessible RocketChat instances. European organizations with exposed RocketChat servers could be targeted by attackers aiming to cause disruption or as part of broader cyber campaigns. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, especially given public disclosure.

1. Immediate mitigation should include restricting external access to RocketChat servers, ideally placing them behind VPNs or firewalls to limit exposure to untrusted networks. 2. Monitor server performance and logs for unusual CPU spikes or repeated failed message parsing attempts that could indicate exploitation attempts. 3. Apply rate limiting on incoming messages or connections to reduce the impact of potential DoS attacks exploiting the regex inefficiency. 4. Engage with RocketChat vendor or community to obtain patches or updates addressing this vulnerability; prioritize upgrading to versions beyond 7.6.1 once available. 5. If patching is delayed, consider implementing input validation or sanitization on the 'line' argument before it reaches the vulnerable regex function, potentially by customizing the server code or using middleware. 6. Conduct regular security assessments and penetration testing focused on messaging platforms to detect similar vulnerabilities proactively. 7. Educate IT and security teams about this vulnerability to ensure rapid response if exploitation signs appear.