Understanding Third-Party Vendor Breaches
Third-party vendor breaches are one of the fastest-growing threats in cybersecurity, exposing sensitive consumer data through compromised vendors and service providers. By targeting external partners connected to an organization’s systems, attackers can circumvent direct security measures to access personal, financial, and medical information, putting individuals at risk of identity theft, economic loss, and long-term privacy harms. Class Action U explains what you need to know.
What Is a Third-Party Vendor Breach?
When you interact with a company online, whether for personal or business purposes, you are also interacting with potentially dozens of third-party vendors that the company works with. These external providers support a range of services, including website functionality, analytics, and more.
Many vendors are granted full access to an organization’s internal network, including sensitive customer data. That access can create a serious security gap.
A data breach occurs when bad actors identify and exploit a vulnerability, in this case, through insecure third-party connections. Standard types of data breach attacks include:
- Email phishing
- Malware
- Brute-force attacks
After gaining access, cybercriminals move laterally through the system, stealing personal data, intellectual property, or financial records to sell, hold for ransom, or use for identity theft.
Third-party breaches introduce a further layer of complexity because the attack surface extends beyond the company’s direct control. By compromising a third-party vendor, hackers no longer have to deal with robust enterprise-level internal defenses. Instead, they may easily penetrate a less-secure vendor and use that access as a backdoor into the primary target.
Unfortunately, because organizations often fail to vet their vendors’ security practices, they remain unaware of the weak links that compromise their cyber integrity. Without monitoring, these breaches may go undetected until it’s too late.
Why Are Third-Party Vendor Breaches Dangerous?
In 2024, third-party breach statistics show that over 35% of all reported breaches were due to a third-party vulnerability. They are among the most serious and complex risks in cybersecurity today, resulting in massive data leaks, identity theft, and financial losses.
Because these breaches originate outside of the company’s direct infrastructure, one of the biggest challenges is determining who is accountable. Furthermore, due to the degrees of separation, there is often a delay in resolving the breach and alerting the affected individuals, leaving many unprotected for extended periods. Once exposed, stolen data is frequently sold or traded on the dark web, a hidden part of the internet where cybercriminals operate anonymously. For victims, it can be difficult, if not impossible, to remove personal information from the dark web once it’s out there.
Examples of Real-World Breaches
One of the most alarming examples is the 2019 SolarWinds breach. This software provider managed the IT networks of thousands of organizations, including Fortune 500 companies and government agencies. Attackers, identified by the U.S. Government as the Russian Foreign Intelligence Service, hid malware inside a software update that clients downloaded because it appeared to be from a trusted source. Through the malware, bad actors gained access to organizations across the public and private sectors, with the primary goal of covert surveillance.
Health care experiences the highest rate of third-party breaches, as well as the highest rate of breaches overall. This was evident in the 2025 breach of Mosaic Life Care, based in St. Joseph, Missouri. The breach was traced to Oracle Health’s compromised data migration servers. Hackers obtained stolen credentials, which they then used to access sensitive medical data, including diagnostic information, birth dates, Social Security numbers (SSNs), and other personal details.
Types of Data Typically Exposed in Vendor Breaches
Data breaches can expose a wide range of sensitive data. The most commonly compromised types of information include:
- Personally Identifiable Information: As the name denotes, PII can identify you. It includes your name, date of birth, SSNs, driver’s license numbers, and home address.
- Financial Records: Bank account numbers and credit card information are frequent targets of breaches.
- Medical Information: Healthcare data may include diagnostic results, medication, treatment histories, and insurance details.
- Login Credentials: This information includes usernames, passwords, and passkeys, which are especially valuable because they open the door to further unauthorized access.
Each data type has unique risks. When such information is exposed together, as often happens in third-party breaches, the consequences multiply, leaving businesses and consumers vulnerable.
What Steps Can You Take After a Third-Party Vendor Breach?
If you’ve received a third-party breach notification in the mail, swift action is essential. Even if you haven’t noticed suspicious activity yet, your personal information can circulate for months or years after a breach.
Start by reviewing the breach notification carefully. Contact the company named in your notification to confirm details and learn about any support they’re offering. Legitimate notices should explain what information was compromised and provide instructions on your next actionable steps. It is common to offer credit monitoring. If available, take advantage of this.
Be wary of any vague or urgent messages. Scammers often utilize a false sense of urgency to prompt you to act quickly without thinking in order to steal more data.
Next, check your bank and credit accounts for unauthorized activity. If financial data was exposed, you can place a fraud alert on your credit file. If your accounts have been accessed, contact your bank immediately. They may advise you to freeze your credit to avoid further harm.
It’s important to change any compromised passwords. For an additional layer of security, enable two-factor authentication when available.
After PII exposure, you will likely experience a rise in spam calls and messages. Do not answer, click any links, or share any information without first verifying the sender.
How To Monitor Your Accounts and Protect Yourself
Whether or not you’ve received a breach notification, it’s important to understand how to identify a data breach and proactively monitor your personal information for signs of misuse. Here’s how:
- Start by reviewing your credit reports from the three major bureaus: Equifax, Experian, and TransUnion.
- Check for unfamiliar accounts or inquiries.
- Enroll in credit monitoring if your SSN was exposed.
- Keep an eye on your insurance explanation of benefits.
To protect yourself moving forward:
- Use strong passwords, unique for each account
- Update your passwords regularly
- Enable multi-factor authentication
- Never click on links from suspicious emails or texts
Stay vigilant—stolen data may be used or sold long after the initial incident.
Join a Class Action Lawsuit
If your personal information was exposed in a third-party vendor breach, you may be eligible to join a class action lawsuit. These types of lawsuits allow groups of affected individuals to collectively pursue compensation from a company that is liable for failing to protect their data.
Businesses have a legal responsibility to safeguard your data. When they fail to do so, directly or via their third-party vendors, you may have the right to sue a company. Lawsuits related to third-party breaches often focus on whether the organization took reasonable steps to select, monitor, and secure its vendors and your data.
Joining a class action can help you recover damages for financial losses, time spent resolving identity theft, emotional distress, and the loss of your private data. In many cases, companies settle these lawsuits to avoid lengthy litigation. They typically offer a combination of financial relief, credit monitoring, and other remedies tailored to the situation.
To get started, look for an active lawsuit that is involved in the breach you were affected by. At Class Action U, we make this easy. You can use our searchable database of ongoing cases. We work with experienced data breach lawyers who can help you understand your legal options and determine whether you can participate in an active case. There’s no cost to reach out and no obligation after speaking with our team or a legal partner.
Take Action Today
If your data was compromised through third-party vendor breaches, now is the time to act. At Class Action U, we believe in leveling the playing field between everyday people and powerful corporations. Our mission is to provide clear guidance, accessible resources, and connections to experienced class action attorneys who know how to take on big businesses.
You don’t have to face the consequences of a data breach alone. Contact us at Class Action U, and we’ll connect you with a lawyer skilled in class action lawsuits. There’s no cost to reach out and no obligation after you speak with our team.
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