O2 Privacy Flaw Sends Users' Mobile Numbers to Visited Websites

o2 logoAs noted by think broadband, a privacy flaw in the way UK carrier O2 handles web traffic on mobile devices has resulted in users' mobile numbers being sent to any website visited from the device as part of the headers in the HTTP requests. While O2 is apparently still investigating the situation, it appears to have the potential for significant privacy-related issues.

If you're reading this news article using your O2 mobile phone, you'll be pleased to know that O2 have already sent us your mobile phone number within the HTTP headers which normally contain information about how content can be displayed on your device. These headers are not normally seen by users, and usually not logged by most websites, but the flaw allows malicious sites to get more personal information about you than you may be willing to share.

For example, if you open an e-mail which includes references to external images, the mere action of opening the e-mail would divulge your phone number. This could be used by anyone undertaking a phishing attack or other scam to get more information from you. The opportunity to abuse this is potentially endless.

The issue was discovered by Twitter user @lewispeckover, who then set up a website to allow users to see what headers are being sent as part of their HTTP requests to websites.

He now notes that the headers coming from his device appear to have stopped showing his mobile phone number, although O2 has yet to issue an official statement on the matter. The company's Twitter account is continuing to blast out responses to concerned users, noting only that the company is looking into the situation and will issue an update when it knows more.

The issue is not exclusive to the iPhone and has the potential to affect all mobile data on the second-largest carrier in the UK, although some users have reported that they are not seeing their mobile numbers appearing in their HTTP request headers. The issue has the potential to for a significant impact on UK iPhone users, as O2 has proven to be a popular choice for iPhone users dating back to its status as the exclusive iPhone carrier in the UK when the device originally launched back in 2007.

Those familiar with the UK's privacy laws have indicated that mobile phone numbers are not considered protected information, but the disclosure of such numbers as part of standard HTTP requests does have the potential to carry implications for users.

Popular Stories

CarPlay Hero

Apple Releases Wireless CarPlay Fix

Wednesday April 16, 2025 11:28 am PDT by
If you have been experiencing issues with wireless CarPlay in your vehicle lately, it was likely due to a software bug that has now been fixed. Apple released iOS 18.4.1 today, and the update's release notes say it "addresses a rare issue that prevents wireless CarPlay connection in certain vehicles." If wireless CarPlay was acting up for you, updating your iPhone to iOS 18.4.1 should...
Beyond iPhone 13 Better Triad

Apple's 20th Anniversary iPhone May Finally Go All Screen

Tuesday April 15, 2025 6:31 am PDT by
Apple is preparing a "bold" new iPhone Pro model for the iPhone's 20th anniversary in 2027, according to Bloomberg's Mark Gurman. As part of what's being described as a "major shake-up," Apple is said to be developing a design that makes more extensive use of glass – and this could point directly to the display itself. Here's the case for Apple releasing a truly all-screen iPhone with no...
iOS 19 Roundup Feature

iOS 19 Will Add These New Features to Your iPhone

Tuesday April 15, 2025 7:37 am PDT by
The first iOS 19 beta is less than two months away, and there are already a handful of new features that are expected with the update. Apple should release the first iOS 19 beta to developers immediately following the WWDC 2025 keynote, which is scheduled for Monday, June 9. Following beta testing, the update should be released to the general public in September. Below, we recap the key...
maxresdefault

iPhone 17 Pro Launching Later This Year With These 12 New Features

Sunday April 13, 2025 7:52 am PDT by
While the iPhone 17 Pro and iPhone 17 Pro Max are not expected to launch until September, there are already plenty of rumors about the devices. Subscribe to the MacRumors YouTube channel for more videos. Below, we recap key changes rumored for the iPhone 17 Pro models as of April 2025: Aluminum frame: iPhone 17 Pro models are rumored to have an aluminum frame, whereas the iPhone 15 Pro and ...
iphone 16 pro models 1

17 Reasons to Wait for the iPhone 17

Thursday April 17, 2025 4:12 am PDT by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models simultaneously, which is why we often get rumored features months ahead of launch. The iPhone 17 series is no different, and we already have a good idea of what to expect from Apple's 2025 smartphone lineup. If you skipped the iPhone...
AirPods Pro 3 Mock Feature

AirPods Pro 3 Just Months Away – Here's What We Know

Friday April 18, 2025 5:16 am PDT by
Despite being more than two years old, Apple's AirPods Pro 2 still dominate the premium wireless‑earbud space, thanks to a potent mix of top‑tier audio, class‑leading noise cancellation, and Apple's habit of delivering major new features through software updates. With AirPods Pro 3 widely expected to arrive in 2025, prospective buyers now face a familiar dilemma: snap up the proven...
iOS 18

Apple Releases iOS 18.4.1 With Bug Fixes

Wednesday April 16, 2025 10:11 am PDT by
Apple today released iOS 18.4.1 and iPadOS 18.4.1, minor updates to the iOS 18 and iPadOS 18 operating systems that came out last September. iOS 18.4.1 and iPadOS 18.4.1 come two weeks after the launch of iOS 18.4 and iPadOS 18.4. The new software can be downloaded on eligible iPhones and iPads over-the-air by going to Settings > General > Software Update. There have been complaints about ...
tvOS 18 Thumb 1

Apple Releases tvOS 18.4.1

Wednesday April 16, 2025 10:04 am PDT by
Apple today released tvOS 18.4.1, a minor update to the tvOS 18 operating system that came out last September. tvOS 18.4.1 comes two weeks after Apple released tvOS 18.4, and it is available for the Apple TV 4K and Apple TV HD models. tvOS 18.4.1 can be downloaded using the Settings app on the ‌Apple TV‌. Open up Settings and go to System > Software Update to get the new software....
iPhone Security Feature 25

Five iPhone Security Features You Should Be Using

Wednesday April 16, 2025 4:15 pm PDT by
Apple has quite a few security features that it's added to iPhones, iPads, and Macs over the years. Now more than ever, it's important to make sure you're taking advantage of the built-in security tools that are available to keep yourself and your data safe, so we've rounded up a list of the most important options. If you don't already have these enabled, you might want to consider turning...

Top Rated Comments

Elijahg Avatar
173 months ago
I've really not been impressed by O2 in recent years. I first joined them in 2006, but ever since then, their network coverage in the 20 mile radius of here (near Bath) hasn't improved one bit. The 3G coverage is absolutely awful. If you aren't in a major town or a city, you have no chance of 3G with O2, only dial-up speed GPRS. Not even EDGE in most cases.

Everything Everywhere are very good, but Three (in the south of England at least) are best by far for 3G coverage.

Perhaps if O2 spent more money on, well, being a service provider and improving their network, rather than all that "priority moments" crap, they might increase their 3G coverage.
Score: 6 Votes (Like | Disagree)
Elijahg Avatar
173 months ago
Not so in my o2 account with an iPhone using iOS 5.0.1 via Safari.

It wasn't inserted into the user agent, it was a separate header: "x-up-calling-line-id".
Score: 4 Votes (Like | Disagree)
japanime Avatar
173 months ago
The "O" is for "Oops!"
Score: 4 Votes (Like | Disagree)
0098386 Avatar
173 months ago
I'm appalled they let this in.

I'm thrilled they fixed it so quickly.

I'm going to treat o2 with a bit more suspicion from here on out.
Score: 2 Votes (Like | Disagree)
The Phazer Avatar
173 months ago
I am now intrigued though as to who the "trusted partners" are. O2 themselves and BT Openzone are the only ones I can think of.

One is Bango, the company that runs O2's adult verification software and thought sending credit card numbers in plaintext over http was a good idea.

O2 might "trust" them. I don't.

Phazer
Score: 2 Votes (Like | Disagree)
4D4M Avatar
173 months ago
I'm perfectly happy with O2, I've found the coverage decent and I don't get loads of junk text messages from them like I did from Vodafone*. This latest gaffe is a bit annoying, but whatever, as a business owner my details are well and truly 'out there' for all the lowlife to exploit anyway. Bring it on scumbags.

*The junk texts don't stop when you leave Vodafone. The other day I received a text that said "Come back to Vodafone and we'll give you a free Windows 7 laptop". If there's one thing that would be guaranteed to STOP me going back to them, it's the threat of a crappy low end piece of junk with a crappy low end OS turning up at my house.
Score: 2 Votes (Like | Disagree)