CVE-2026-76783: DeDeCMS SQL Injection Vulnerability

CVE-2026-76783 Overview

CVE-2026-76783 is a SQL injection vulnerability affecting DeDeCMS version 53_1_UTF8. The flaw resides in the /plus/advancedsearch.php script, where the sql parameter is passed to a database query without adequate sanitization. Remote attackers can manipulate this argument to inject arbitrary SQL statements against the underlying database. The vulnerability requires no authentication and no user interaction, and the exploit has been publicly disclosed. The issue is classified under [CWE-74] (Improper Neutralization of Special Elements in Output Used by a Downstream Component).

Critical Impact
Unauthenticated remote attackers can inject SQL through the sql parameter in advancedsearch.php, enabling data disclosure, modification, or deletion within the DeDeCMS database.

Affected Products

DeDeCMS 53_1_UTF8
Deployments exposing /plus/advancedsearch.php to untrusted networks
Any downstream forks that reuse the vulnerable advancedsearch.php handler

Discovery Timeline

2026-08-20 - CVE-2026-76783 published to NVD
2026-08-20 - Last updated in NVD database

Technical Details for CVE-2026-76783

Vulnerability Analysis

The vulnerability exists in the advanced search feature of DeDeCMS 53_1_UTF8. The advancedsearch.php endpoint accepts a user-controlled sql parameter and incorporates it into a database query without adequate validation or parameterization. Because the endpoint is reachable over the network and requires no authentication, an attacker can send crafted HTTP requests to execute arbitrary SQL statements. Successful exploitation allows the attacker to enumerate table structures, read sensitive records, modify content, or corrupt data within the CMS database. The exploit has been disclosed publicly, increasing the likelihood of opportunistic attacks against exposed installations. Refer to the VulDB entry for CVE-2026-76783 for additional technical context.

Root Cause

The root cause is improper neutralization of special elements in the sql argument processed by /plus/advancedsearch.php. The affected code path concatenates attacker-supplied input into SQL queries rather than using prepared statements or strict input validation, mapping directly to [CWE-74].

Attack Vector

The attack vector is network-based. An unauthenticated remote attacker sends an HTTP request to /plus/advancedsearch.php with a manipulated sql parameter. No privileges or user interaction are required. The vulnerability manifests through URL parameter tampering. See the Feishu Wiki technical writeup for a description of the injection point.

Detection Methods for CVE-2026-76783

Indicators of Compromise

HTTP requests to /plus/advancedsearch.php containing SQL keywords such as UNION, SELECT, SLEEP, INFORMATION_SCHEMA, or comment sequences like -- and /* in the sql parameter.
Unusual query patterns or error responses from the DeDeCMS database referencing malformed SQL syntax.
Sudden spikes in outbound data from the web server or database host following requests to the advanced search endpoint.

Detection Strategies

Deploy web application firewall (WAF) signatures that flag SQL metacharacters within query parameters targeting /plus/.
Enable database query logging and alert on statements originating from the CMS user that reference system tables or unexpected schemas.
Correlate web access logs with database audit logs to identify anomalous query volumes tied to the search endpoint.

Monitoring Recommendations

Monitor web server logs for repeated requests to advancedsearch.php from a single source IP.
Track response length and status code anomalies for the /plus/advancedsearch.php URL.
Alert on database errors surfaced in application logs that reference syntax issues in advanced search queries.

How to Mitigate CVE-2026-76783

Immediate Actions Required

Restrict network access to /plus/advancedsearch.php using WAF rules or reverse proxy allowlists until a fix is applied.
Audit database accounts used by DeDeCMS and enforce least privilege to limit the impact of injection.
Review historical access logs for evidence of prior exploitation attempts against the advanced search endpoint.

Patch Information

No vendor patch is referenced in the published advisory. Administrators should track the VulDB vulnerability record for updates and apply an official fix from the DeDeCMS project when released.

Workarounds

Disable or remove the /plus/advancedsearch.php script if the advanced search functionality is not required.
Deploy WAF rules that block requests containing SQL syntax in the sql parameter of the advanced search endpoint.
Apply input validation at the reverse proxy layer to reject requests with non-alphanumeric characters in the sql argument.

bash

# Example nginx rule to block requests containing SQL metacharacters
# targeting the vulnerable endpoint
location /plus/advancedsearch.php {
    if ($arg_sql ~* "(union|select|sleep|information_schema|--|/\*)") {
        return 403;
    }
}