Some customers of The UPS Store may have had their credit and debit card information exposed by a computer virus found on systems at 51 stores in 24 states.

A spokeswoman for UPS says the information includes names, card numbers and postal and email addresses from about 100,000 transactions between Jan. 20 and Aug. 11.

United Parcel Service Inc. said Wednesday that it was among U.S. retailers who got a Department of Homeland Security bulletin about the malware on July 31. The malware is not identified by current anti-virus software.

The company is not aware of any fraud related to the attack, spokeswoman Chelsea Lee said.

Atlanta-based UPS said it hired a security firm that found the virus in systems at about 1 percent of the company’s 4,470 franchised locations. At many stores, the intrusion did not begin until March or April.

Lee said that the problem was fixed by Aug. 11 and the company took additional steps to protect systems at other stores. She said the affected stores were not linked electronically, and UPS is still investigating how they were compromised.

UPS said it is providing identity protection and credit monitoring help to affected customers.

The affected stores were in Arizona, California, Colorado, Connecticut, Florida, Georgia, Idaho, Illinois, Louisiana, Maryland, Nebraska, Nevada, New Jersey, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Virginia and Washington.

From the company’s description, the breach appeared far smaller than one that hit Target Corp. during the holiday-shopping season, when hackers stole credit and debit card information involving millions of customers. Fallout from the incident is still hurting profits. Target, which said Wednesday that second-quarter profit fell 62 percent, has spent $235 million related to the breach, partly offset by $90 million in insurance payments.

The UPS breach won’t have a material financial impact on the company, Lee said.

Last week, Supervalu said that hackers might have stolen names, account numbers, expiration dates and other information from card holders who shopped at up to 200 of its grocery and liquor stores. Restaurant operator P.F. Chang’s, Goodwill thrift stores and other retailers have been hit by data breaches.