Apple's C1 Modem Gets First Security Update in iOS 18.5

The iOS 18.5 update that Apple released today includes a security fix for the iPhone 16e's C1 modem, which is the first Apple-designed modem.

Apple iPhone 16e C1 Feature
According to Apple's security support document for iOS 18.5, there's a fix for a vulnerability with the C1 modem. Apple says that it addressed a baseband security flaw that could allow an attacker "in a privileged network position" to intercept network traffic. Basically, a hacker that had access to cellular network infrastructure could potentially exploit the vulnerability for surveillance or to employ a man-in-the-middle attack.

The C1's baseband is used for signal processing, so it encodes and decodes data for communication between devices and networks, and processes calls, texts, and data connections. Apple addressed the vulnerability with improved state management, which could mean new validation checks to prevent attackers from exploiting weaknesses between operational states.

Apple released the ‌iPhone 16e‌ earlier this year, and today's security update is notable because it marks the first security flaw discovered and addressed in the C1 modem.

iOS 18.5 also includes several other security fixes for vulnerabilities with image processing, call history, Bluetooth, file parsing, FaceTime, Notes, ProRes, WebKit, and more. None of the vulnerabilities fixed today were known to have been actively exploited, but it's still a good idea to update right away.

Related Roundup: iPhone 16e
Buyer's Guide: iPhone 16e (Caution)
Related Forum: iPhone

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'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...
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...
iOS 26

iOS 26.3 and iOS 26.4 Will Add These New Features to Your iPhone

Tuesday February 3, 2026 7:47 am PST by
We are still waiting for the iOS 26.3 Release Candidate to come out, so the first iOS 26.4 beta is likely still at least a week or two away. Following beta testing, iOS 26.4 will likely be released to the general public in March or April. Below, we have recapped known or rumored iOS 26.3 and iOS 26.4 features so far. iOS 26.3 iPhone to Android Transfer Tool iOS 26.3 makes it easier...
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...

Top Rated Comments

mk313 Avatar
10 months ago
I'm a little surprised at how well the Apple Designed modems appear to be working. When Apple moved to the Intel Modems, there was a lot of pushback on the performance relative to the Qualcomm ones. It seems like people are satisfied with the Apple designed ones (for the most part) which is hopefully good news for the future.
Score: 6 Votes (Like | Disagree)
TechTexan Avatar
10 months ago

I'm a little surprised at how well the Apple Designed modems appear to be working. When Apple moved to the Intel Modems, there was a lot of pushback on the performance relative to the Qualcomm ones. It seems like people are satisfied with the Apple designed ones (for the most part) which is hopefully good news for the future.
I haven’t had any issues with mine, works the same if not better then my last phone.
Score: 5 Votes (Like | Disagree)
Unregistered 4U Avatar
10 months ago

Yes, I am also surprised how well the first iteration went. But I also remember the naysayers when the first M1 came out and it was beating Intel and AMD chips, people were skeptical and blamed flawed testing.
The countdown is on for when the EU will say that Apple using their own modems is anticompetitive and it doesn’t allow competition in the Apple cellular modem market. :)
Score: 4 Votes (Like | Disagree)
Hurda Avatar
10 months ago

but older versions are usually patched as well.
But not necessarily all known bugs are patched in these versions.

https://support.apple.com/guide/deployment/about-software-updates-depc4c80847a/web#dep25a4a6565
Note: Because of dependency on architecture and system changes to any current version of Apple operating systems (for example, macOS 15, iOS 18, and so on), not all known security issues are addressed in previous versions (for example, macOS 14, iOS 17, and so on).
Score: 2 Votes (Like | Disagree)
I7guy Avatar
10 months ago

('https://www.macrumors.com/2025/05/12/apple-ios-18-5-c1-security-fix/')

[…]

iOS 18.5 also includes several other security fixes for vulnerabilities with image processing, call history, Bluetooth, file parsing, FaceTime, Notes, ProRes, WebKit, and more. None of the vulnerabilities fixed today were known to have been actively exploited, but it's still a good idea to update right away.

Article Link: Apple's C1 Modem Gets First Security Update in iOS 18.5 ('https://www.macrumors.com/2025/05/12/apple-ios-18-5-c1-security-fix/')
The above is useful information for the main news article.
Score: 2 Votes (Like | Disagree)
iBluetooth Avatar
10 months ago

I'm a little surprised at how well the Apple Designed modems appear to be working. When Apple moved to the Intel Modems, there was a lot of pushback on the performance relative to the Qualcomm ones. It seems like people are satisfied with the Apple designed ones (for the most part) which is hopefully good news for the future.
Yes, I am also surprised how well the first iteration went. But I also remember the naysayers when the first M1 came out and it was beating Intel and AMD chips, people were skeptical and blamed flawed testing.
Score: 2 Votes (Like | Disagree)