DedeCMS up to 5.8.1-beta /plus/flink.php ShowMsg code injection

Summaryinfo

A vulnerability identified as critical has been detected in DedeCMS up to 5.8.1-beta. Affected is the function ShowMsg of the file /plus/flink.php. Performing a manipulation results in code injection. This vulnerability only affects products that are no longer supported by the maintainer. This vulnerability is cataloged as CVE-2021-48016. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability classified as critical has been found in DedeCMS up to 5.8.1-beta. This affects the function ShowMsg of the file /plus/flink.php. The manipulation with an unknown input leads to a code injection vulnerability. CWE is classifying the issue as CWE-94. The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

DedeCMS through 5.8.1-beta contains a PHP code injection vulnerability in ShowMsg() where the HTTP Referer header is written into a DedeTemplate string and included. Unauthenticated attackers can send a crafted Referer to /plus/flink.php?dopost=save with an empty validate code to execute arbitrary PHP and system commands. Exploitation evidence was first observed by the Shadowserver Foundation on 2023-10-14.

It is possible to read the advisory at srcincite.io. This vulnerability is uniquely identified as CVE-2021-48016 since 10/14/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/22/2026). The attack technique deployed by this issue is T1059 according to MITRE ATT&CK.

By approaching the search of inurl:plus/flink.php it is possible to find vulnerable targets with Google Hacking.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Content Management System

Name

• DedeCMS

Version

• 5.8.1-beta

License

• commercial

Support

• end of life

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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