Feeds from thousands of Trendnet home security cameras have been breached, allowing any web user to access live footage without needing a password.
Internet addresses which link to the video streams have been posted to a variety of popular messageboard sites.
Users have expressed concern after finding they could view children’s bedrooms, among other locations.
US-based Trendnet says it is in the process of releasing updates to correct a coding error introduced in 2010.
It said it had emailed customers who had registered affected devices to alert them to the problem.
However, a spokesman told the BBC that “roughly 5%” of purchasers had registered their cameras and it had not yet issued a formal media release – despite being aware of the problem for more than three weeks.
“We first became aware of this on 12 January,” said Zak Wood, Trendnet’s director of global marketing.
“As of this week we have identified 26 [vulnerable] models. (In) seven of the models, the firmware has been tested and released.
“We anticipate to have all of the revised firmware available this week. We are scrambling to discover how the code was introduced and at this point it seems like a coding oversight.”
Mr Wood added that the California-based firm estimated that “fewer than 1,000 units” might be open to this threat in the UK, but could not immediately provide an exact global tally beyond saying that it was “most likely less than 50,000”.
Tech news website The Verge first publicised the issue last week after discovering a blog which had published details of the vulnerability on 10 January.
The author discovered that after setting up one of the cameras with a password, its video stream became accessible to anyone who typed in the correct net address.
In each case, this consisted of the user’s IP address followed by an identical sequence of 15 characters.
The writer then showed how the Shodan search engine – which specialises in finding online devices – could be used to discover cameras vulnerable to the flaw.
“Last I ran this there was something like 350 vulnerable devices that were available,” the author wrote at the time.
However, it appears that others then took advantage of the technique to expose other links and uploaded them to the net.
Within two days, a list of 679 web addresses had been posted to one site, and others followed – in some cases listing the alleged Google Maps locations associated with each camera.
Messages on one forum included: “Someone caught a guy in denmark (traced to ip) getting naked in the bathroom.” Another said: “I think this guy is doing sit-ups.”
One user wrote “baby spotted”, causing another to comment: “I feel like a paedophile watching this.”
Some screenshots have also been uploaded.
The firm – whose slogan is “networks that people trust” – said it had halted shipments of affected products to retailers and that any delivery received since the start of this month should be safe. However, it said that items delivered at an earlier date might need a firmware update.
“We are just getting to that point to be able to succinctly convey more information to the public who would be concerned,” said Mr Wood.
“We are planning an official release of information to the public concerning this, but in advance I can tell you that this week we are targeting to have firmware to all affected models.”
At the time of interview, Trendnet’s home page and its press release section made no mention of the problem.
However, a warning was later added to its front page linking to a statement that says: “It is Trendnet’s understanding that video from select Trendnet IP cameras may be accessed online in real time. Upon awareness of the issue, Trendnet initiated immediate actions to correct and publish updated firmware which resolves the vulnerability.”