The recent cybersecurity breach at the Pierce County Library System (PCLS) has put the personal information of over 340,000 individuals at risk. Discovered in April 2025, the attack highlights significant vulnerabilities in our digital infrastructure, especially within public organizations that serve vast communities. Operating across 19 locations and catering to nearly one million residents near Seattle, the library system is taking this incident very seriously after unauthorized access to its network was confirmed.
In breach notification letters made public on PCLS’s website and distributed to regulatory bodies in various states, the timeline of the incident has been detailed. The data breach is reported to have occurred between April 15 and 21, 2025. PCLS detected the breach on April 21 and responded promptly by shutting down their systems to limit the attack and initiate an investigation.
Details of the Data Exposure
The investigation found that the attackers had unauthorized access to PCLS systems for nearly a full week, during which sensitive information was exfiltrated. By May 12, the library system confirmed that the compromised data involved both library patrons and employees—current and former.
For the library patrons, the exposed information consisted mainly of names and dates of birth. On the other hand, the data breach impacted employees and their family members far more severely. The compromised personal information possibly includes Social Security numbers, financial account details, driver’s license numbers, credit card information, passport numbers, health insurance records, medical details, and dates of birth.
PCLS has stated that while they are not currently aware of any misuse of the compromised data, they recognize the serious nature of the breach. The organization stressed its commitment to safeguarding the confidentiality and privacy of personal information entrusted to its care.
Attackers Identified
In a troubling twist, the INC ransomware gang, a group known for high-profile attacks on governmental and public-sector entities, claimed responsibility for the Pierce County Library System breach in May. This gang is infamous for targeting organizations like the Pennsylvania Office of the Attorney General and emergency warning services utilized by numerous municipalities across the United States.
PCLS has not explicitly confirmed if a ransom was demanded or paid. However, it’s worth noting that ransomware attacks on public libraries are becoming increasingly common, as cybercriminals often believe that government-funded systems will pay to quickly restore access to vital services.
Ongoing Cybersecurity Challenges in Pierce County
This incident is not unprecedented for Pierce County. In 2023, a ransomware attack disrupted the county’s public bus service, impacting systems utilized by around 18,000 riders daily. Such recurring events underscore the persistent challenges local governments face in protecting crucial public infrastructure from cyber threats.
Globally, library systems have witnessed a surge in cyberattacks. Notable incidents, including a significant attack on the British Library, alongside multiple attacks targeting libraries across Canada and the U.S., have resulted in extended service outages and disruptions.
Advice for Those Affected
PCLS is advising individuals whose information may have been compromised to remain vigilant against potential identity theft and fraud. The library system recommends that patrons routinely check their bank and credit card statements for any unusual activity, in addition to monitoring their credit reports closely.
U.S. law allows consumers to obtain one free credit report each year from each of the three major credit bureaus: Equifax, Experian, and TransUnion. Individuals are also encouraged to place fraud alerts or credit freezes on their accounts at no cost, which helps prevent unauthorized accounts from being opened in their names.
To assist those affected, PCLS has established a dedicated call center to address questions or concerns related to the incident. As the library continues to expand its digital offerings, it becomes increasingly essential to invest in robust cybersecurity measures to keep personal information safe.
