zhblue hustoj up to 26.01.01 ranklist_export Nickname csv injection

Summaryinfo

A vulnerability classified as critical was found in zhblue hustoj up to 26.01.01. This issue affects the function ranklist_export. The manipulation of the argument Nickname results in csv injection. This vulnerability was named CVE-2026-23873. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability was found in zhblue hustoj up to 26.01.01. It has been classified as critical. Affected is the function ranklist_export. The manipulation of the argument Nickname with an unknown input leads to a csv injection vulnerability. CWE is classifying the issue as CWE-1236. The product saves user-provided information into a Comma-Separated Value (CSV) file, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as a command when the file is opened by a spreadsheet product. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

hustoj is an open source online judge based on PHP/C++/MySQL/Linux for ACM/ICPC and NOIP training. All versions are vulnerable to CSV Injection (Formula Injection) through the contest rank export functionality (contestrank.xls.php and admin/ranklist_export.php). The application fails to sanitize user-supplied input (specifically the "Nickname" field) before exporting it to an .xls file (which renders as an HTML table but is opened by Excel). If a malicious user sets their nickname to an Excel formula when an administrator exports and opens the rank list in Microsoft Excel, the formula will be executed. This can lead to arbitrary command execution (RCE) on the administrator's machine or data exfiltration. A fix was not available at the time of publication.

The advisory is available at github.com. This vulnerability is traded as CVE-2026-23873 since 01/16/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. Successful exploitation requires user interaction by the victim. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 02/27/2026).

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

The vulnerability is also documented in the databases at CNNVD (CNNVD-202601-3451) and EUVD (EUVD-2026-4200). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Vendor

• zhblue

Name

• hustoj

Version

• 26.01.01

Website

• Product: https://github.com/zhblue/hustoj/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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