CVE-2025-15005 identifies a security vulnerability in CouchCMS, an open-source content management system, specifically affecting versions 2.0 through 2.4. The issue is located in the reCAPTCHA handler component within the couch/config.example.php file, where the arguments K_RECAPTCHA_SITE_KEY and K_RECAPTCHA_SECRET_KEY are manipulated to use hard-coded cryptographic keys. Hard-coded keys pose a significant security risk because they are static and can be extracted by attackers, undermining the cryptographic protections intended by reCAPTCHA integration. This flaw allows remote attackers to exploit the system without requiring authentication or user interaction, although the attack complexity is high, making exploitation challenging. The vulnerability has a CVSS 4.0 base score of 6.3, reflecting medium severity, with network attack vector, high attack complexity, and no privileges or user interaction needed. The impact primarily concerns the confidentiality and integrity of the reCAPTCHA mechanism, potentially enabling attackers to bypass bot detection or manipulate cryptographic operations dependent on these keys. While no known exploits are currently active in the wild, a public exploit has been released, increasing the risk of future attacks. The absence of patches at the time of reporting necessitates immediate mitigation efforts by users of affected CouchCMS versions. Organizations should audit their CMS configurations to identify hard-coded keys and replace them with securely generated, unique keys. Additionally, monitoring for updates or patches from CouchCMS developers is critical to fully remediate the vulnerability.

For European organizations, this vulnerability could lead to unauthorized bypass of reCAPTCHA protections, increasing the risk of automated attacks such as credential stuffing, spam, or brute force attempts on web applications using CouchCMS. Compromise of cryptographic keys may also affect data confidentiality and integrity where these keys are used beyond reCAPTCHA, potentially exposing sensitive user data or enabling further exploitation. Given CouchCMS's usage in small to medium-sized enterprises and niche web projects, the impact may be more pronounced in sectors relying on these CMS deployments for public-facing websites or customer portals. Disruption or compromise of these services could damage organizational reputation, lead to regulatory non-compliance under GDPR if personal data is exposed, and incur financial losses. The medium severity rating reflects the balance between the difficulty of exploitation and the potential damage. However, the public availability of an exploit increases the urgency for mitigation. Organizations with limited cybersecurity resources may be particularly vulnerable to exploitation attempts leveraging this flaw.

1. Immediately audit all CouchCMS installations to identify if versions 2.0 through 2.4 are in use and check for hard-coded cryptographic keys in configuration files, especially couch/config.example.php and any deployed configurations derived from it. 2. Replace any hard-coded K_RECAPTCHA_SITE_KEY and K_RECAPTCHA_SECRET_KEY values with unique, securely generated keys obtained from the official reCAPTCHA service or equivalent trusted sources. 3. Isolate and restrict access to configuration files to prevent unauthorized reading or modification. 4. Monitor CouchCMS official channels for patches or updates addressing this vulnerability and apply them promptly once available. 5. Implement additional web application firewalls (WAF) rules to detect and block suspicious traffic patterns that may indicate exploitation attempts targeting reCAPTCHA bypass. 6. Conduct regular security assessments and penetration testing focusing on authentication and bot mitigation mechanisms. 7. Educate web administrators and developers on the risks of hard-coded keys and enforce secure coding practices to avoid similar issues in future deployments. 8. Consider migrating to alternative CMS platforms if CouchCMS support or patching is delayed or unavailable.