CVE intelligence and bounded remediation

CVE-2026-23873 — hustoj is an open source online judge based on PHP/C++/MySQL/Linux for ACM/ICPC and NOIP training

Critical CVSS 9

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.

Severity
Critical
CVSS
9 (3.1)
Published
2026-01-22
CISA KEV
Not currently listed
Ecosystem
windows/system
Weaknesses
CWE-1236

Affected products

  • hustoj / hustoj

Matched remediation archetype

General vulnerability remediation

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Confirm the affected component, deployment paths, reachable interfaces, and enabled features from inventories and configuration, without probing production destructively.
  • Compare the advisory's affected conditions with the repository lockfiles, build manifests, artifacts, and runtime inventory.
  • Identify data sensitivity, trust boundaries, and privilege level for every confirmed affected deployment.

Remediate safely

  • Apply a vendor-supported fix or remove the affected component or feature; record the selected change and its source in the repository.
  • Update direct and transitive dependency locks, generated artifacts, deployment manifests, and asset inventories together.
  • Add a regression test for the documented unsafe condition using inert inputs and preserve rollback instructions.

Authoritative sources

Complete CVE record and remediation plan

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