Link Previews in Popular Messaging Apps May Lead to Security Vulnerabilities

A new report by security researchers Talal Haj Bakry and Tommy Mysk has revealed that link previews in messaging apps can lead to security and privacy issues on iOS and Android. Through link previews, Bakry and Mysk discovered that apps could leak IP addresses, expose links sent in end-to-end encrypted chats, download large files without users' consent, and copy private data.

link preview example signal

Link previews offer a peek at content such as web pages or documents in many messaging apps. The feature allows users to see a short summary and preview image inline with the rest of the conversation without having to tap on the link.

Apps such as iMessage and WhatsApp ensure that the sender generates the preview, meaning that the receiver is protected from risk if the link is malicious. This is because the summary and preview image are created on the sender's device and sent as an attachment. The receiver's device will show the preview as it was transmitted from the sender without having to open the link. Apps that do not generate a link preview at all, such as TikTok and WeChat, are also unaffected.

The issue arises when the receiver generates the link preview, because the app will automatically open the link in the background to create the preview. This occurs before users even tap on the link, potentially exposing them to malicious content. Apps such as Reddit generate links in this way.

For example, a malicious actor could send a link to their own server. When the receiver's app automatically opens the link in the background, it would send the device's IP address to the server, revealing their location.

This approach can also cause issues if the link points to a large file, whereupon the app may attempt to download the whole file, draining battery life and hemorrhaging data plan limits.

Link previews can also be generated on an external server, and this is how many popular apps such as Discord, Facebook Messenger, Google Hangouts, Instagram, LinkedIn, Slack, Twitter, and Zoom work. In this case, the app will first send the link to an external server and ask it to generate a preview, and then the server will send the preview back to both the sender and receiver.

However, this may pose a security threat when the contents of the sent link are private. Using an external server allows these apps to potentially create unauthorized copies of private information and retain it for a period of time.

Although many of the apps had implemented a data limit on how much of any link content to download, the researchers discovered that Facebook Messenger and Instagram were particularly notable for downloading the entirety of any link's contents to its servers, regardless of size. When questioned about this behavior, Facebook reportedly said that it considers this to be "working as intended."

Copies kept on external servers could be subject to data breaches, which may be particularly concerning for users of business apps such as Zoom and Slack, and those who send links to sensitive private data.

The research offers an appreciation of how the same exact feature can work in different ways, and how these differences can have a significant impact on security and privacy. See the full report for more information.

Popular Stories

M5 MacBook Pro

Apple Announces New 14-Inch MacBook Pro With M5 Chip

Wednesday October 15, 2025 6:07 am PDT by
Apple today updated the 14-inch MacBook Pro base model with its new M5 chip, which is also available in updated iPad Pro and Vision Pro models. In addition, the base 14-inch MacBook Pro can now be configured with up to 4TB of storage on Apple's online store, whereas the previous model maxed out at 2TB. However, the maximum amount of unified RAM available for this model remains 32GB. Like...
Apple iPad Pro hero M5

Apple Debuts New iPad Pro With M5 Chip, Faster Charging, and More

Wednesday October 15, 2025 6:16 am PDT by
Apple today announced the next-generation iPad Pro, featuring the custom-designed M5, C1X, and N1 chips. The M5 chip has up to a 10-core CPU, with four performance cores and six efficiency cores. It features a next-generation GPU with Neural Accelerator in each core, allowing the new iPad Pro to deliver up to 3.5x the AI performance than the previous model, and a third-generation ray-tracing ...
iphone air thickness

Apple Said to Cut iPhone Air Production Amid Underwhelming Sales

Friday October 17, 2025 8:29 am PDT by
Apple plans to cut production of the iPhone Air amid underwhelming sales performance, Japan's Mizuho Securities believes (via The Elec). The Japanese investment banking and securities firm claims that the iPhone 17 Pro and iPhone 17 Pro Max are seeing higher sales than their predecessors during the same period last year, while the standard iPhone 17 is a major success, performing...
maxresdefault

Here's Everything Apple Announced Today

Wednesday October 15, 2025 3:54 pm PDT by
We didn't get a second fall event this year, but Apple did unveil updated products with a series of press releases that went out today. The M5 chip made an appearance in new MacBook Pro, Vision Pro, and iPad Pro models. Subscribe to the MacRumors YouTube channel for more videos. We've rounded up our coverage and highlighted the main feature changes for each device below. MacBook Pro M5...
HomePod mini and Apple TV

Apple's Next Rumored Products: New HomePod Mini, Apple TV, and More

Thursday October 16, 2025 9:13 am PDT by
Apple on Wednesday updated the 14-inch MacBook Pro, iPad Pro, and Vision Pro with its next-generation M5 chip, but previous rumors have indicated that the company still plans to announce at least a few additional products before the end of the year. The following Apple products have at one point been rumored to be updated in 2025, although it is unclear if the timeframe for any of them has...
Vision Pro M5 Announcement

Apple Updates Vision Pro With M5 Chip, Dual Knit Band, and 120Hz Support

Wednesday October 15, 2025 6:14 am PDT by
Apple today updated the Vision Pro headset with its next-generation M5 chip for faster performance, and a more comfortable Dual Knit Band. The M5 chip has a 10-core CPU, a 10-core GPU with Neural Accelerators, and a 16-core Neural Engine, and we have confirmed the Vision Pro still has 16GB of RAM. With the M5 chip, the Vision Pro offers faster performance and longer battery life compared...
14 inch MacBook Pro Keyboard

New 14-Inch MacBook Pro Has Two Key Upgrades Beyond the M5 Chip

Thursday October 16, 2025 8:31 am PDT by
Apple on Wednesday updated the 14-inch MacBook Pro base model with an M5 chip, and there are two key storage-related upgrades beyond that chip bump. First, Apple says the new 14-inch MacBook Pro offers up to 2× faster SSD performance than the equivalent previous-generation model, so read and write speeds should get a significant boost. Apple says it is using "the latest storage technology," ...
MacBook Pro M5 Screen

New MacBook Pro Does Not Include a Charger in the Box in Europe

Wednesday October 15, 2025 6:59 am PDT by
The new 14-inch MacBook Pro with an M5 chip does not include a charger in the box in European countries, including the U.K., Ireland, Germany, Italy, France, Spain, the Netherlands, Norway, and others, according to Apple's online store. In the U.S. and all other countries outside of Europe, the new MacBook Pro comes with Apple's 70W USB-C Power Adapter, but European customers miss out....
airpods max 2024 colors

AirPods Max 2: Everything We Know So Far

Tuesday October 14, 2025 8:43 am PDT by
Apple's AirPods Max have now been available for almost five years, so what do we know about the second-generation version? According to Apple supply chain analyst Ming-Chi Kuo, the new AirPods Max will be lighter than the current ones, but exactly how much is as yet known. The current AirPods Max weigh 0.85 pounds (386.2 grams), excluding the charging case, making it one of the heavier...
macbook pro blue

Apple's M5 MacBook Pro Imminent: What to Expect

Tuesday October 14, 2025 4:35 pm PDT by
Apple is going to launch a new version of the MacBook Pro as soon as tomorrow, so we thought we'd go over what to expect from Apple's upcoming Mac. M5 Chip The MacBook Pro will be one of the first new devices to use the next-generation M5 chip, which will replace the M4 chip. The M5 is built on TSMC's more advanced 3-nanometer process, and it will bring speed and efficiency improvements. ...

Top Rated Comments

jayducharme Avatar
65 months ago

Although many of the apps had implemented a data limit on how much of any link content to download, the researchers discovered that Facebook Messenger and Instagram were particularly notable for downloading the entirety of any link's contents to its servers, regardless of size.
And why does this not surprise me?
Score: 19 Votes (Like | Disagree)
macintoshmac Avatar
65 months ago

These automatic link previews are a cancer, when I am sending a link I don't need a preview, I know what I am sending.
Link previews are targeted at receivers who would appreciate a quick preview, not towards previews that are shown on sender's devices as well when senders send messages.
Score: 10 Votes (Like | Disagree)
doboy Avatar
65 months ago
Got it, use only iMessage :)
Score: 4 Votes (Like | Disagree)
Apple Freak Avatar
65 months ago

Rotary phones without answering machines and letter writing: It's the only solution!
Don't forget about smoke signals and carrier pigeons too.
Score: 3 Votes (Like | Disagree)
jonblatho Avatar
65 months ago

Security researchers do not agree on people not wanting it. They are commenting on misuse of autoamtic link preview.
To expand on this, they’re specifically taking issue with only some implementations which can create privacy and security risks. Granted, nothing that they discuss here is that bad or difficult to fix.
Score: 3 Votes (Like | Disagree)
Runs For Fun Avatar
65 months ago
It's interesting in this case (and probably many others) how there is a direct tradeoff between device security and data privacy.

If everything is generated externally and only a preview image is sent to your device, there is no security risk to your device (unless you open the link), but a privacy disadvantage.

If everything is generated on-device, there's no privacy issue in terms of third party services, but there is a privacy issue if the link is being used maliciously to track the user, and there's a potential security risk if there's a vulnerability on the page that requires no user interaction.

Of course, on the privacy side, if any sensitive content being linked to doesn't require a login, then it is only offering security by obscurity, which is so bad from a security standpoint already, so that's kind of a moot point. You likewise shouldn't be pushing passwords or whatnot in the URL.

Which is to say the researchers are right that the potential privacy hit is better than the potential local security hit, although I'm loathe to say that when Facebook is involved since you can be pretty sure they're going to use this to abusively harvest and store any user data they possibly can.

I don't see Apple Messages anywhere on that list, and I know it generates previews, so I'm assuming they're the redacted one?

Interestingly, I've noticed that Messages will generate a preview of links from contacts in my address book, but does NOT generate a preview of links from other contacts. So I don't get previews from spam links or things like UPS tracking alerts, but I do get them from friends and co-workers.

This isn't perfect from a security standpoint, but seems like a not-so-bad compromise.
iMessage generates the preview one the sender’s device which is the correct way to do this. The problem here is some crappy third party apps don’t do this and/or have no size limit for what is fetched for the preview.
Score: 3 Votes (Like | Disagree)