CVE-2026-23873

CRITICAL
2026-01-22 [email protected]
9.0
CVSS 3.1
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CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

3
Analysis Generated
Mar 12, 2026 - 21:54 vuln.today
PoC Detected
Feb 27, 2026 - 15:02 vuln.today
Public exploit code
CVE Published
Jan 22, 2026 - 00:15 nvd
CRITICAL 9.0

Tags

Linux PHP MySQL Hustoj

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.

Analysis

HUSTOJ online judge system has a CSV injection vulnerability in all versions that allows code execution through crafted submissions exported to spreadsheets.

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Remediation

Within 24 hours: Identify all affected systems and apply vendor patches immediately. Monitor vendor channels for patch availability.

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Priority Score

65
Low Medium High Critical
KEV: 0
EPSS: +0.0
CVSS: +45
POC: +20

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CVE-2026-23873 vulnerability details – vuln.today
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