CVE-2026-23873

CRITICALNVD 9.09.0
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This critical-severity CVE scores 9.0 under NVD CVSS v3. EPSS exploit probability: 0.6% (47th percentile of EPSS-scored CVEs). No GitHub Security Advisory CVSS is on record for this CVE.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, NVD CVSS v3
Elevated

Also known asEUVD-2026-4200 (ENISA EUVD)Source: ENISA EUVD

9.0EG
EchelonGraph verdictPlan mitigationNo fix is confirmed yet: check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule (the SSVC decision on this page).
  • CISA's Vulnrichment rates exploitation as PoC; EchelonGraph holds no exploit-code reference for it
CISA-KEV: Not listedEPSS PROB: 0.6%CVSS: 9.0Exploit: No code on recordExposed services: Not assessed

No fix is confirmed yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for the fix.

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.

CVSS v3
9.0
EG Score
9.0CRITICALmedium confidence
EG Risk
57
EG Risk 57/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity90% × 45%
Impact severity (EG Severity): CVSS 9.0 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation40% × 40%
EchelonGraph's fixed weight for EG-KEV Tier 3 (Elevated): a constant, not a probability.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Track* at high (mission-essential systems).
Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule.
EPSS PROB
0.6%
EPSS %ILE
47th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.0): severity, escalated by confirmed exploitation. This CVE's 9.0 is its impact severity (EG Severity), not escalated.

EG Severity
9.0 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.6% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-01). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Track* at high (mission-essential systems).CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Track* at high (mission-essential systems).

No fix is confirmed yet. Check the vendor's advisory for a fixed release; until one is applied, restrict network exposure of the affected system or apply the vendor's mitigation on your normal schedule.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

No released fix is confirmed on this page, but CISA's timeline does not wait for a fix's release: it starts when an agency identifies the flaw on an asset and updates the CDM Agency and Federal Dashboard, and the directive counts patching, decommissioning the system or another action as remediation. Until a fixed release is applied, mitigate as this page's verdict says. In the directive's words, “Fix on system upgrade” means that, “unless conditions change”, the vulnerability “should be remediated the next time the vulnerable asset receives a scheduled major upgrade or rebuild”: its timelines are “dynamic as facts change”, and a KEV listing shortens them.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

January 22, 2026

Last Modified

June 17, 2026

Advisory Details (1)

Auto-updated Jun 8, 2026
No fix on record yet. Sources: github.
GitHub advisoryMentions a patch (unverified)

Stored CSV Injection (Formula Injection) in Contest Rank Export Leading to RCE Risk · Advisory · zhblue/hustoj · GitHub

https://github.com/zhblue/hustoj/security/advisories/GHSA-gqwv-v7vx-2qjw

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 13× in last 7d / 56× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 99 of 221 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. 1 repeat row among the latest 100 is merged into the row it repeats. The 122 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-02 05:32 UTCEG score recompute
  2. 2026-11-01 16:34 UTCEPSS rescoreEPSS 0.6% · 47th percentile
  3. 2026-11-01 06:09 UTCEG score recompute
  4. 2026-10-31 16:32 UTCEPSS rescoreEPSS 0.6% · 47th percentile
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  19. 2026-10-24 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  1. 2026-10-21 10:43 UTCEG score recompute
  2. 2026-10-20 16:32 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  4. 2026-10-19 16:31 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  10. 2026-10-16 16:41 UTCEPSS rescoreEPSS 0.6% · 46th percentile
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  23. 2026-10-11 13:48 UTCEPSS rescoreEPSS 0.6% · 45th percentile
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  26. 2026-10-09 10:25 UTCOSV refresh
  27. 2026-10-08 17:11 UTCEPSS rescoreEPSS 0.6% · 45th percentile
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  41. 2026-09-19 17:30 UTCOSV refresh
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Frequently asked(5)

What is CVE-2026-23873?
CVE-2026-23873 is a critical-severity vulnerability; its CVE record was published on January 22, 2026. 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…
When was the CVE record for CVE-2026-23873 published?
The CVE record for CVE-2026-23873 was published on January 22, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of June 17, 2026; the record at its source may have been updated since.
Is CVE-2026-23873 actively exploited?
CVE-2026-23873 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.6% probability of exploitation in the next 30 days (47th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-23873?
CVE-2026-23873 has a CVSS v3 base score of 9.0 (NVD).
How do I remediate CVE-2026-23873?
No fix for CVE-2026-23873 is confirmed yet. Until one is published, restrict network exposure of the affected system or apply the vendor's mitigation — for example, keep it off the internet or limit it to trusted networks — and watch the vendor's advisory for the fix.

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