Goldman Sachs has warned investors in some of its alternative investment funds that their data may have been compromised due to a cybersecurity breach at one of the bank's law firms.

In a letter dated December 19, Goldman Sachs stated it had received notification from Fried Frank Harris Shriver & Jacobson LLP, which serves as external legal counsel for multiple Goldman alternative funds, of a "cybersecurity incident." Goldman Sachs said it is communicating with the law firm "to better understand whether our data or client data may have been exposed."

"Goldman Sachs's systems were not impacted by this incident and remain secure," a Goldman Sachs spokesperson said. "We continue to work diligently, as always, to protect our clients and their data."

The letter was included in a proposed class-action lawsuit filed against Fried Frank on Wednesday, with the plaintiff being Andrew Sacks, an investor in Goldman's Petershill Private Equity Seeding II Offshore Fund.

A Fried Frank spokesperson said in a statement: "We moved quickly to contain the incident and engaged leading external data security experts to assist in our response, validate the security of our systems, and we have reported this matter to law enforcement." The firm added that its client services were not affected.

According to the letter, Fried Frank informed Goldman Sachs that its network is now secure, the vulnerability that led to the data exposure has been remediated, and stated that any exposed data is "unlikely to be disseminated or misused."

"We are conducting an independent assessment of Fried Frank's security controls to validate the effectiveness of their remediation," Goldman Sachs stated in the letter. "Data security is of critical importance, and we take it very seriously."