Schule Has Insecure OTP Length, is Susceptible to Brute-Force Attacks
Schule is open-source school management system software. The generateOTP() function generates a 4-digit numeric One-Time Password (OTP). Prior to version 1.0.1, even if a secure random number generator is used, the short length and limited range (1000–9999) results in only 9000 possible combinations. This small keyspace makes the OTP highly vulnerable to brute-force attacks, especially in the absence of strong rate-limiting or lockout mechanisms. Version 1.0.1 fixes the issue.
- Published
- May 22, 2025
- Updated
- Jun 17, 2026
- EPSS
- 0.3% · 17th percentile
- CWE
- CWE-521
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Report tools
Action score
26
Monitor
Low priority for now.
- CVSS
- 26 / 40 · 6.6 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.3%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 6.6
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| schule111 | schule school management system | cpe:2.3:a:schule111:schule_school_management_system |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- schule111 schule school management system1.0.0
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
schule111 Schule
- < 1.0.1affected
Same product
schule111: all recordsOther highest-scoring records for the same primary product.
- CVE-2025-48375Schule Missing Rate Limiting on OTP Email Requests – Susceptible to Abuse & DoS26Monitor
- CVE-2025-48373Schule Has Client-Side Role-Based Access Control (RBAC) Bypass Vulnerability26Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- X
Weakness class (CWE)
CWE-521 · Weak Password RequirementsCVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/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
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Brute ForceCAPEC-112High
- Dictionary-based Password AttackCAPEC-16likelihood: Medium · High
- Password Brute ForcingCAPEC-49likelihood: Medium · High
- KerberoastingCAPEC-509High
- Rainbow Table Password CrackingCAPEC-55likelihood: Medium · Medium
- Remote Services with Stolen CredentialsCAPEC-555Very High
- Windows Admin Shares with Stolen CredentialsCAPEC-561
- Password SprayingCAPEC-565likelihood: High · High
ATT&CK techniques
- Remote ServicesT1021
- Remote Services:SMB/Windows Admin SharesT1021.002
- Valid Accounts:Default AccountsT1078.001
- Brute ForceT1110
- Brute Force:Password GuessingT1110.001
- Brute Force:Password CrackingT1110.002
- Brute Force:Password SprayingT1110.003
- Email Collection:Remote Email CollectionT1114.002
- External Remote ServicesT1133
- Steal or Forge Kerberos Tickets:KerberoastingT1558.003
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- github.com/schule111/Schule/commit/cd53abbea93943f2c60a5281d45bebadc57636b7
- github.com/schule111/Schule/security/advisories/GHSA-6c48-67xx-vqgc
Vendor advisories and official records. Exploit/PoC links are deliberately left out.