US health giant Kaiser hit by data breach — millions of customers informed they could be at risk

Data leak
(Image credit: Shutterstock)

American healthcare giant Kaiser Foundation Health Plan exposed sensitive data on millions of its current and former patients, apparently by mistake. 

Among the data inadvertently shared with advertisers are member names and IP addresses, and information regarding their membership status with Kaiser Permanente. Furthermore, the company leaked information on how members interacted with the website and the apps, and what they searched for in the health encyclopedia. 

A total of 13.4 million people are affected by this mishap, the company has confirmed, adding it is preparing to send out data leak notifications to all of them.

Targeting healthcare

The company confirmed the news via a statement shared with TechCrunch, noting its website and mobile applications used “certain online technologies”(tracking codes) that may have transmitted personal information to third-party vendors, thought to include Google, Microsoft, and X. 

Kaiser filed a notice with the U.S. government, and notified California’s attorney general of what had happened.

Due to the sensitivity of the data they hold, healthcare organizations are a constant target for cybercriminals. Recently, Change Healthcare suffered a major ransomware attack in which the threat actors stole 4TB of valuable files. In exchange for keeping the data private and not sharing it on the dark web, the attackers demanded $22 million in cryptocurrency. 

In late 2023, after a supply chain attack on ESO Solutions, sensitive data from a number of healthcare organizations in the US was stolen, and in March of the same year, both Zoll Medical and Independent Living Systems reported data breaches.

The Kaiser Foundation Health Plan is the parent organization of Kaiser Permanente, and claimed to have more than 12 million members last year.

More from TechRadar Pro

Sead is a seasoned freelance journalist based in Sarajevo, Bosnia and Herzegovina. He writes about IT (cloud, IoT, 5G, VPN) and cybersecurity (ransomware, data breaches, laws and regulations). In his career, spanning more than a decade, he’s written for numerous media outlets, including Al Jazeera Balkans. He’s also held several modules on content writing for Represent Communications.

Read more
ID theft
Over a million patients potentially hit after another US healthcare provider hit by cyberattack
ransomware avast
The biggest addiction treatment provider in the US says it was hit by data breach
Lock on Laptop Screen
United Healthcare data breach may have affected 190 million Americans
healthcare
Over a million clinical records exposed in data breach
Data Breach
Thousands of healthcare records exposed online, including private patient information
Cartoon Phishing
One of the largest data leaks ever sees info on 1.5 billion people leaked online
Latest in Security
Data leak
Top home hardware firm data leak could see millions of customers affected
Representational image depecting cybersecurity protection
Third-party security issues could be the biggest threat facing your business
A stylized depiction of a padlocked WiFi symbol sitting in the centre of an interlocking vault.
Broadcom warns of worrying security flaws affecting VMware tools
Android Logo
Devious new Android malware uses a Microsoft tool to avoid being spotted
URL phishing
HaveIBeenPwned owner suffers phishing attack that stole his Mailchimp mailing list
Ransomware
Cl0p resurgence drives ransomware attacks to new highs in 2025
Latest in News
Buzz Lightyear Space Ranger Spin Rennovations
Disney’s giving a classic Buzz Lightyear ride a tech overhaul – here's everything you need to know
Hisense U8 series TV on wall in living room
Hisense announces 2025 mini-LED TV lineup, with screen sizes up to 100 inches – and a surprising smart TV switch
Nintendo Music teaser art
Nintendo Music expands its library with songs from Kirby and the Forgotten Land and Tetris
Opera AI Tabs
Opera's new AI feature brings order to your browser tab chaos
An image of Pro-Ject's Flatten it closed and opened
Pro-Ject’s new vinyl flattener will fix any warped LPs you inadvertently buy on Record Store Day
The iPhone 16 Pro on a grey background
iPhone 17 Pro tipped to get 8K video recording – but I want these 3 video features instead