Vulnerability · Published Jan 21, 2026 · Assigned by GitHub_M
CVE-2026-23873HUSTOJ is Vulnerable to Stored CSV Injection (Formula Injection) in Contest Rank Export
Medium 5.2
In plain English
A medium-severity security flaw in hustoj from zhblue. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities).
Official description
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.
Affected products (as reported)
Weakness: CWE-1236 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:A/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H
References
- https://github.com/zhblue/hustoj/security/advisories/GHSA-gqwv-v7vx-2qjw x_refsource_CONFIRM