Adminer is open-source database management software. Adminer v5.4.1 and earlier has a version check mechanism where adminer.org sends signed version info via JavaScript postMessage, which the browser then POSTs to ?script=version. This endpoint lacks origin validation and accepts POST data from any source. An attacker can POST version[] parameter which PHP converts to an array. On next page load, openssl_verify() receives this array instead of string and throws TypeError, returning HTTP 500 to all users. Upgrade to Adminer 5.4.2.
The CVSS score for this vulnerability is 7.5, categorizing it as high severity. The attack vector is network-based with low complexity and requires no privileges or user interaction to exploit.
Risk to organizations includes potential denial of service affecting all users of the application. Attackers may leverage this vulnerability to disrupt service availability, which could result in significant operational impact.
Organizations should prioritize patching immediately to mitigate this vulnerability and protect their systems.
Vulnerability Details
The vulnerability arises from a version check mechanism in Adminer. The affected versions include all versions prior to 5.4.2. The CVE was published on February 9, 2026.
Technical Analysis
The root cause of this vulnerability is the lack of origin validation on the version check endpoint. As a result, any attacker can send a crafted POST request with a malicious version[] parameter, which is processed incorrectly by the PHP backend.
The attack vector is network-based with low complexity. No privileges are required, and no user interaction is necessary, making exploitation straightforward.
The impact on availability is high, as the vulnerability can lead to a service outage for all users of the Adminer application.
Risk & Impact Analysis
Organizations using Adminer are at risk of denial of service due to this vulnerability. The potential blast radius includes all instances of the application. Given the high CVSS score, organizations should address this vulnerability in their priority patch cycle.
Exploitation Status
Signal | Status |
|---|---|
Known Exploit | Yes |
Public PoC | Yes |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The vulnerability affects Adminer versions 4.6.2 to 5.4.1. All versions prior to the vendor patch (5.4.2) are vulnerable.
Mitigation & Remediation
To mitigate this vulnerability, organizations should upgrade to Adminer 5.4.2 immediately. If patching is not possible, consider implementing network controls to restrict access to the affected endpoint.
Detection Guidance
Monitor logs for unusual POST requests to the version check endpoint. Look for signs of exploitation, such as TypeErrors in application logs.
AppSecure Threat Intelligence Insight
This vulnerability highlights the importance of proper validation mechanisms in web applications. Security teams should review existing implementations to ensure robust validation is in place.
For more insights, consider reviewing our guide on penetration testing methodology and how it can help identify similar vulnerabilities.
Additionally, explore our resources on vulnerability management programs to better prepare for future threats.
Finally, engage with our insights on security testing best practices to reinforce your application security strategy.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
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