CVE-2026-23873
Last modified
CVE-2026-23873 is a critical-severity vulnerability rated 9/10 on the CVSS scale. 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). EPSS estimates a 0.51% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Hustoj | Hustoj | <= 26.01.31 |
References
- https://github.com/zhblue/hustoj/security/advisories/GHSA-gqwv-v7vx-2qjwExploit, Mitigation, Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
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