Now Patched 'Sign in With Apple' Bug Left Users Open to Attack

Researcher Bhavuk Jain in April discovered a critical Sign in With Apple vulnerability that could have resulted in a takeover of some user accounts. The bug was specific to third party apps that used Sign in With Apple and didn't implement additional security measures.

SigninwithApple e1590865553423
Jain notes that Sign in With Apple works by authenticating a user through a JWT (JSON Web Token) or a code that's generated by Apple's server. Apple then gives users the option to share either the email tied to their Apple ID or a private relay email address,which creates a JWT that's used to log in a user.

Jain then discovered that once JWTs for both Apple ID emails and private relay email addresses were requested and the token's signature was verified using Apple's public key, it "showed as valid." Should the bug have not been discovered, a JWT could be created and used to gain access to one's account.

In an interview with The Hacker News, Jain spoke about the severity of the bug:

The impact of the this vulnerability was quite critical as it could have allowed a full account takeover. Many developers have integrated Sign in with Apple since it is mandatory for applications that support other social logins. To name a few that use Sign in with Apple - Dropbox, Spotify, Airbnb, Giphy (now acquired by Facebook).

According to Jain, Apple conducted an investigation and concluded that no accounts were compromised using this method before the vulnerability was patched. Jain was paid $100,000 by Apple under its Apple Security Bounty Program for reporting the bug.

Popular Stories

Aston Martin CarPlay Ultra Screen

Apple's CarPlay Ultra to Expand to These Vehicle Brands Later This Year

Sunday February 1, 2026 10:08 am PST by
Last year, Apple launched CarPlay Ultra, the long-awaited next-generation version of its CarPlay software system for vehicles. Nearly nine months later, CarPlay Ultra is still limited to Aston Martin's latest luxury vehicles, but that should change fairly soon. In May 2025, Apple said many other vehicle brands planned to offer CarPlay Ultra, including Hyundai, Kia, and Genesis. In his Powe...
Apple Logo Black

Apple Just Made Its Second-Biggest Acquisition Ever After Beats

Thursday January 29, 2026 10:07 am PST by
Apple today confirmed to Reuters that it has acquired Q.ai, an Israeli startup that is working on artificial intelligence technology for audio. Apple paid close to $2 billion for Q.ai, according to sources cited by the Financial Times. That would make this Apple's second-biggest acquisition ever, after it paid $3 billion for the popular headphone and audio brand Beats in 2014. Q.ai has...
Apple Logo Black

Apple's Next Launch is 'Imminent'

Sunday February 1, 2026 12:31 pm PST by
The calendar has turned to February, and a new report indicates that Apple's next product launch is "imminent," in the form of new MacBook Pro models. "All signs point to an imminent launch of next-generation MacBook Pros that retain the current form factor but deliver faster chips," Bloomberg's Mark Gurman said on Sunday. "I'm told the new models — code-named J714 and J716 — are slated...
14 inch MacBook Pro Keyboard

Apple Changes How You Order a Mac

Saturday January 31, 2026 10:51 am PST by
Apple recently updated its online store with a new ordering process for Macs, including the MacBook Air, MacBook Pro, iMac, Mac mini, Mac Studio, and Mac Pro. There used to be a handful of standard configurations available for each Mac, but now you must configure a Mac entirely from scratch on a feature-by-feature basis. In other words, ordering a new Mac now works much like ordering an...
Apple MacBook Pro M4 hero

New MacBook Pros Reportedly Launching Alongside macOS 26.3

Sunday February 1, 2026 5:42 am PST by
Apple is planning to launch new MacBook Pro models with M5 Pro and M5 Max chips alongside macOS 26.3, according to Bloomberg's Mark Gurman. "Apple's faster MacBook Pros are planned for the macOS 26.3 release cycle," wrote Gurman, in his Power On newsletter today. "I'm told the new models — code-named J714 and J716 — are slated for the macOS 26.3 software cycle, which runs from...

Top Rated Comments

SBlue1 Avatar
74 months ago
100,000? Well deserved. :)
Score: 13 Votes (Like | Disagree)
B4U Avatar
74 months ago
Are we getting numb with the constant SW issues that Apple is having lately?
Score: 11 Votes (Like | Disagree)
Peace Avatar
74 months ago
I’m getting burned out on timmys security problems .

windows is looking better
Score: 10 Votes (Like | Disagree)
I7guy Avatar
74 months ago

I’m getting burned out on timmys security problems .

windows is looking better
Windows is better? Sure windows is as tight as a drum as far as that goes.

Just keep patching them Timmy.
Score: 7 Votes (Like | Disagree)
cmaier Avatar
74 months ago

I don't care.

I'm done updating.

I'm sick and tired of my phone being artificially slowed.

I'm back to using Linux for things that need to be secure, like banking, etc.
You know this wasn’t a bug in the client software or operating system, right?
Score: 5 Votes (Like | Disagree)
konqerror Avatar
74 months ago

If it was unexploited and has been patched, there's not much of a story here… except to other businesses that might consider Sign In With Apple.
Bugs are a symptom, not the flaw. The constant stream of problems coming out from Apple shows their software development and QA processes are severely flawed.
Score: 5 Votes (Like | Disagree)