CVE-2023-26118 is a vulnerability classified as a Regular Expression Denial of Service (ReDoS) affecting Angular version 1.4.9. The root cause is an insecure regular expression used in the URL validation logic of the <input type="url"> HTML element. This regular expression is susceptible to catastrophic backtracking when processing specially crafted, large input strings. Catastrophic backtracking occurs when the regex engine exhaustively tries many permutations to match the input, leading to excessive CPU consumption and application unresponsiveness. Since Angular 1.4.9 is an older version of the popular front-end framework, applications still using it may be vulnerable if they accept user input through URL fields without additional safeguards. The vulnerability can be exploited remotely without requiring authentication or user interaction, making it a network-exploitable denial of service vector. The CVSS v3.1 score is 5.3 (medium severity), reflecting the lack of impact on confidentiality or integrity but a clear impact on availability. No patches or fixes are linked in the provided data, so mitigation may require upgrading Angular to a later, fixed version or applying custom input validation and rate limiting. No known exploits have been reported in the wild, but the vulnerability is publicly disclosed and documented. The CWE associated is CWE-1333, which relates to ReDoS issues caused by vulnerable regular expressions. This vulnerability primarily threatens web applications that rely on Angular 1.4.9 for client-side URL input validation, potentially leading to denial of service conditions under attack.

For European organizations, the primary impact of CVE-2023-26118 is on the availability of web applications that use Angular 1.4.9 and accept URL inputs via the vulnerable <input type="url"> element. An attacker can remotely trigger high CPU usage on client or server-side components processing the input, causing application slowdowns or crashes. This can disrupt business operations, degrade user experience, and potentially lead to service outages. Since the vulnerability does not affect confidentiality or integrity, data breaches or unauthorized data modifications are not a concern here. However, denial of service attacks can be leveraged as part of larger attack campaigns or to distract from other malicious activities. European organizations with legacy web applications, especially in sectors like government, finance, and critical infrastructure, may face operational risks if they have not updated Angular or implemented compensating controls. The medium severity score suggests moderate risk, but the ease of exploitation and lack of authentication requirements increase the threat landscape. Additionally, public-facing applications are more exposed, increasing the likelihood of exploitation attempts. The absence of known exploits in the wild reduces immediate risk but does not eliminate the need for mitigation.

1. Upgrade Angular from version 1.4.9 to the latest stable release where this vulnerability is fixed, as relying on outdated frameworks increases security risks. 2. If upgrading is not immediately feasible, implement server-side input validation to reject overly long or suspicious URL inputs before they reach the vulnerable regex processing. 3. Apply rate limiting and request throttling on endpoints accepting URL inputs to reduce the impact of potential ReDoS attacks. 4. Use Web Application Firewalls (WAFs) configured to detect and block anomalous input patterns that could trigger catastrophic backtracking. 5. Monitor application performance metrics and logs for signs of unusual CPU spikes or slowdowns indicative of ReDoS exploitation attempts. 6. Educate development teams about the risks of insecure regular expressions and encourage secure coding practices, including the use of safe regex patterns and input sanitization. 7. Conduct security testing, including fuzzing and regex performance testing, on input validation components to identify and remediate similar vulnerabilities proactively. 8. Maintain an inventory of legacy software components and prioritize their upgrade or replacement to reduce attack surface.