Short answer
Yonsei University said on 22 October 2026 that personal information of some members had leaked through unauthorized access to its portal service. Reports put the number at about 10,000 students and graduates. The school says resident registration numbers were not included, and police have started a preliminary inquiry.
If you think your details were included, start with our checklist on what to do after a data breach.
Key facts
| Organization | Yonsei University |
|---|---|
| Incident type | Data breach |
| Status | Confirmed by the organization |
| Sector | Higher education |
| Country | South Korea |
| Disclosed | 2026-10-22 |
| People or records affected | About 10,000 current students and graduates (one outlet reported about 15,000) |
What data was exposed
- Student ID numbers
- Mobile phone numbers
- Email addresses
- Some system management information
What happened
Yonsei University in Seoul said on 22 October 2026 that personal information of some members had leaked after an unauthorized external party accessed its portal service. SBS Biz reports that about 10,000 current students and graduates are affected. The university’s Information and Communications Office issued a notice and apologized.
What was exposed
The leaked items are student ID numbers, mobile phone numbers, email addresses and some system management information. The university said resident registration numbers and other unique identifiers or sensitive data were not included. The date of the intrusion was not given in the Yonhap or SBS reports we reviewed.
What the university and police are doing
Yonsei said it blocked the leak route after confirming the breach and referred the case to investigators. It posted item-by-item details on the notice board of its main website. According to Yonhap, via Supple, the Seoul Metropolitan Police Agency’s Cyber Crime Investigation Unit has opened a preliminary inquiry to find out how the data leaked and how large the damage is. We have not seen a finding on the cause.
Why contact details and student IDs are enough for phishing
A student ID plus a phone number and email lets a scammer write a message that looks like it comes from the school office. Our phishing messages guide and government and institution impersonation guide show common lures, and the data breach checklist lists the first steps.
What students and graduates should do
Start with the university’s own notice, since it lists what was exposed for each person. Then treat any message that mentions your student ID as unverified until you confirm it through the school’s official site or phone line. Phone numbers and emails are the most useful data for scammers here, because they can be used to send fake “account locked” or “tuition payment” notices. If you reuse your portal password on other accounts, change it everywhere and turn on two-step verification for your email. Graduates should also watch their alumni email for fake certificate, donation or job offers, which are common lures after a school leak.
What to watch next
Watch for the police result and any Personal Information Protection Commission action. The incident is one of many Korean campus and corporate leaks reported this month. See the others on our breaches page.
Scams to watch for after this breach
Criminals use breach news as cover. Expect messages that mention the incident, quote real details, or offer help.
- Fake emails or texts posing as the university, asking you to log in to 'verify' your student account.
- Phishing that uses your student ID to look genuine, for example about tuition, scholarships or certificates.
- Voice phishing or smishing to the phone number on your record, posing as police or a bank.
- Fake job or part-time work offers sent to graduates' email addresses.
What to do if you are affected
- 01Check the item-by-item notice on Yonsei's official website to see what was exposed for you.
- 02Be careful with messages that appear to come from the university, especially ones asking for a login or payment. The school warns about messages impersonating it.
- 03Go to the portal by typing the address yourself, and change your portal password.
- 04Do not share one-time passwords or move money at a caller's request, whoever they claim to be.
- 05Report suspicious texts to KISA on 118 and voice phishing to the police on 112.
Frequently asked questions
What data leaked from Yonsei?
Student ID numbers, mobile phone numbers, email addresses and some system management information. The university says resident registration numbers and other unique identifiers or sensitive data were not included.
How many people are affected?
About 10,000 current students and graduates, according to SBS Biz and Yonhap. One other outlet reported a higher figure, and the exact count may change.
Is the police investigating?
Yonhap reports the Seoul Metropolitan Police Agency's Cyber Crime Investigation Unit has opened a preliminary inquiry (naesa) into how the data leaked and how many people are affected.
Where can I see whether my data was involved?
Yonsei said it would post item-by-item information on the notice board of its main website.
Sources
- Yonsei hack leaks data of students and graduates (Korean-language article, headline in English), SBS Biz, 2026-10-22
- Yonsei portal hack leaks about 10,000 people's data; police open inquiry (Korean-language article, headline in English), Yonhap News (via Supple), 2026-10-22
This post summarises public reporting as of 2026-11-06. Details of live incidents change; we update posts when the organization or regulators publish new facts. Spot an error? See our editorial and corrections policy.