CVE-2023-26117 identifies a Regular Expression Denial of Service (ReDoS) vulnerability in Angular version 1.0.0, specifically within the $resource service. The root cause is an insecure regular expression that, when processing a large and specially crafted input, leads to catastrophic backtracking—a condition where the regex engine consumes excessive CPU cycles attempting to match the input. This results in a denial of service by degrading application responsiveness or causing server crashes. The vulnerability is remotely exploitable without requiring authentication or user interaction, increasing its risk profile. The affected Angular version is notably old, and no patches or fixes are currently linked, indicating that remediation may require upgrading to a later, secure Angular version or applying custom mitigations. The CVSS v3.1 score of 5.3 (medium severity) reflects the vulnerability’s impact on availability (no confidentiality or integrity impact), ease of exploitation (network accessible, no privileges needed), and scope (affects all instances running Angular 1.0.0). No known exploits have been reported in the wild, but the vulnerability’s nature makes it a potential vector for denial of service attacks against web applications relying on this Angular version.

For European organizations, the primary impact is on the availability of web applications or APIs that utilize Angular 1.0.0’s $resource service. Successful exploitation can lead to service outages or degraded performance, affecting user experience and potentially causing operational disruptions. Sectors such as e-commerce, government digital services, and financial services that rely on Angular-based frontends or backends may experience downtime or increased operational costs due to mitigation efforts. While confidentiality and integrity are not directly impacted, denial of service can indirectly affect business continuity and reputation. Organizations with legacy systems or those slow to update dependencies are at higher risk. Additionally, the vulnerability could be leveraged as part of a multi-vector attack to distract or exhaust resources during more complex intrusions.

1. Upgrade Angular to a version later than 1.0.0 where this vulnerability is addressed or no longer present. Since no direct patch links are provided, moving to a maintained Angular version is recommended. 2. Implement strict input validation on all data entering the $resource service to reject unusually large or malformed inputs that could trigger catastrophic backtracking. 3. Apply rate limiting and request throttling at the web server or API gateway level to reduce the impact of repeated malicious requests. 4. Monitor application performance metrics and logs for signs of excessive CPU usage or slow response times indicative of ReDoS attempts. 5. Where upgrading is not immediately feasible, consider isolating vulnerable components behind web application firewalls (WAFs) configured to detect and block suspicious payloads targeting regex vulnerabilities. 6. Educate development teams on secure coding practices around regular expressions and dependency management to prevent recurrence.