MyRecon OSINT
McKesson
On 21 August 2026, McKesson was breached. 6,404,340 accounts were exposed, including dates of birth, email addresses, employers. MyRecon rates it 73/100 — severe. That is about 24% of the population of Australia.
What happened
In August 2026, healthcare and pharmaceutical company McKesson was targeted in a ShinyHunters "pay or leak" extortion campaign. The group subsequently published a substantial corpus of data they alleged was sourced from the company, which included 6.4M unique email addresses among other personal and corporate data attributes. The impacted data related to a range of individuals and roles, including marketing campaign recipients, patients, staff and healthcare provider contacts. In McKesson's disclosure notice, the company advised it had identified unauthorised access to "certain third-party applications and the exfiltration of certain data was associated with a subset of customers within our Oncology & Multispecialty and Medical-Surgical business units", but had "reasonable assurance of no ongoing unauthorized activity".
Breach description from Have I Been Pwned, used under a CC BY 4.0 licence.
Read the original disclosure ↗
Who was behind it
No party has been publicly confirmed as responsible, and this page will not name one. Most breaches are never formally attributed: data surfaces on a forum or inside a combined dump long after the intrusion, and the trail back to a specific actor is rarely made public. Where a group has claimed responsibility it is usually named in the account above — that claim is theirs, not a finding of ours.
What was exposed, and why it matters
- Dates of birthOne of the three things call centres ask to verify identity, and it never changes.
- Email addressesThe address becomes a confirmed, active target — expect more phishing, better aimed.
- EmployersConnects a personal account to a workplace, which is how attackers pivot from a person to a company.
- GendersSmall on its own; useful to anyone assembling a fuller profile.
- NamesTurns an anonymous address into an identified person, which is what makes targeted phishing possible.
- Personal health dataAdds detail to a profile that can be assembled from several breaches at once.
- Phone numbersEnables SIM-swap attacks against SMS two-factor codes, and puts the number on scam-call lists indefinitely.
- Physical addressesWhere someone actually lives. Combined with a name this moves the risk off the internet.
What to do if you were in it
- Move two-factor authentication off SMS and onto an authenticator app, which a SIM swap cannot intercept.
- Be sceptical of post and callers who already know your address — knowing it is no longer evidence of anything.
- Expect better-aimed phishing. A message that already knows your name and where you have an account is the whole point of a breach like this.
Questions people ask about this breach
Was my email address in the McKesson breach?
Enter it in the box at the top of this page. MyRecon checks it against this breach and every other one on record, and the address is never stored.
What data was leaked in the McKesson breach?
dates of birth, email addresses, employers, genders, names, personal health data, phone numbers, physical addresses. Each one is explained above, along with what it means for the person it belongs to.
When did it happen, and when did it become public?
The breach is dated 21 August 2026. It was published to Have I Been Pwned on 10 September 2026, a gap of 20 days during which the data was already out.
Is the McKesson breach real?
Yes. Have I Been Pwned lists it as verified, meaning the data was checked against the source rather than taken on trust.
How many people were affected?
6,404,340 accounts. That is about 24% of the population of Australia. That is accounts rather than people — one person often has several.
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Severity is scored by MyRecon from the number of accounts, the sensitivity of the specific fields exposed, and whether the breach is confirmed — not by a language model. The description above is quoted from Have I Been Pwned; the analysis around it is ours.