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CVE-2026-23873

9.0 · CRITICAL

hustoj is an open source online judge based on PHP/C++/MySQL/Linux for ACM/ICPC and NOIP training.

Published Jan 22, 2026CWE-1236EPSS 0.57%

Overview

CVE-2026-23873 is a critical-severity vulnerability. It was published on January 22, 2026 and has a CVSS 3.1 base score of 9.0 (CRITICAL).

This vulnerability has a CVSS 3.1 base score of 9.0, rated CRITICAL. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/zhblue/hustoj/security/advisories/GHSA-gqwv-v7vx-2qjw

How CyberStrike helps

Frequently asked questions

What is CVE-2026-23873?

CVE-2026-23873 is a critical-severity vulnerability. It was published on January 22, 2026 and has a CVSS 3.1 base score of 9.0 (CRITICAL).

How severe is CVE-2026-23873?

This vulnerability has a CVSS 3.1 base score of 9.0, rated CRITICAL. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2026-23873?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-23873?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-23873 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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