Telstra has said that an error in its website's search function led to 18 customers' personal information including name, business name, address, phone number, and email address being breached.
According to Telstra, it accidentally made these details available to three customers via its Your Telstra Tools online help service for small business and enterprise customers.
"We take the privacy and security of our customers extremely seriously, so we took the immediate step to disable Your Telstra Tools while our IT Security team investigated," a blog post by head of Sales and Service Michael Ackland said.
"The team identified emails from Telstra to 18 customers about planned network interruptions had been made available to three customers who performed a specific search on the site. The issue was caused by an error in the system's search function."
Ackland added that Telstra has begun notifying and apologising to the affected customers, and will "remain vigilant to keep our data and systems safe and secure".
The blog post followed reports by Nine News on Friday that one customer had gained access to a Telstra database with the details of 66,500 customers' names, addresses, phone numbers, and email addresses by searching the term "email" on the telco's website after logging in to his account.
This included the details of a Department of Defence employee, Nine reported.
Telstra had earlier on Monday announced that it will be axing CFO Warwick Bray and group executive of Technology, Innovation and Strategy Stephen Elop, along with group general counsel Will Irving and group executive of Media Joe Pollard.
In total, 8,000 jobs will be axed as part of the Telstra2022 restructure announced by CEO Andy Penn last month, with the Communications Workers Union (CWU) claiming that the telco is offering a "disgraceful and insulting pay offer" for those being made redundant.
"1.5 percent each year for Workstream employees, along with a 1.5 percent pay pool offer for Job Family employees, meaning some Job Family employees may not even receive 1.5 percent," CWU reported on Friday.
"This, along with the removal of Job Family bonuses from the EA, gives Job Family employees no guaranteed individual pay outcome whatsoever -- management are in full control.
"Whilst we have locked in your conditions, your union cannot support Andy's disgraceful pay offer and Telstra is refusing to hold any further discussions on the matter."
Telstra has unveiled a string of changes to its leadership team, including appointing COO Robyn Denholm as its new CFO after the departure of Warwick Bray, with former Nokia CEO and head of technology and innovation Stephen Elop also leaving.
ZDNet unpacks the main points of Telstra's new three-year strategy, including the establishment of InfraCo and Global Business Services, and how it will handle NBN, 5G, and TPG.
Telstra wants to take away customers' pain by removing excess data charges and additional service charges, as well as providing more entertainment offerings by year's end, the telco's group executive of Consumer and Small Business Vicki Brady has told ZDNet.
Telstra will invest AU$5 billion in its networks over the next three years, CEO Andy Penn has said, while the telco's new 'Peace of Mind Data' solution will reduce excess data charges across its mobile plans.
Telstra's head of networks Mike Wright has announced that he will be stepping down.
The Telstra2022 three-year program will see 8,000 jobs cut from the telco.