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 (Neutral)
Related Forum: iPhone

Popular Stories

iOS 26

iOS 26.4 and iOS 27 Features Revealed in New Leak

Friday December 12, 2025 10:56 am PST by
Macworld's Filipe Espósito today revealed a handful of features that Apple is allegedly planning for iOS 26.4, iOS 27, and even iOS 28. The report said the features are referenced within the code for a leaked internal build of iOS 26 that is not meant to be seen by the public. However, it appears that Espósito and/or his sources managed to gain access to it, providing us with a sneak peek...
apple beta 26 lineup

Apple Leak Confirms Work on Foldable iPhone, AirTag 2, and Dozens More Devices

Monday December 15, 2025 2:05 pm PST by
Last week, details about unreleased Apple devices and future iOS features were shared by Macworld. This week, we learned where the information came from, plus we have more findings from the leak. As it turns out, an Apple prototype device running an early build of iOS 26 was sold, and the person who bought it shared the software. The OS has a version number of 23A5234w, and the first...
Apple Logo Top Half

Early iOS 26 Software Leak Uncovers Dozens of Upcoming Apple Features

Monday December 15, 2025 3:05 pm PST by
Software from an iPhone prototype running an early build of iOS 26 leaked last week, giving us a glimpse at future Apple devices and iOS features. We recapped device codenames in our prior article, and now we have a list of some of the most notable feature flags that were found in the software code. In some cases, it's obvious what the feature flags are referring to, while some are more...
Apple Foldable Thumb

Leak Reveals Foldable iPhone Details

Monday December 15, 2025 9:09 am PST by
The first foldable iPhone will feature a series of design and hardware firsts for Apple, according to details shared by the Weibo leaker known as Digital Chat Station. According to a new post, via machine translation, Apple is developing what the leaker describes as a "wide foldable" device, a term used to refer to a horizontally oriented, book-style foldable with a large internal display....
iOS 26

Apple Releases iOS 26.2 With Alarms for Reminders, Lock Screen Changes, Enhanced Safety Alerts and More

Friday December 12, 2025 10:10 am PST by
Apple today released iOS 26.2, the second major update to the iOS 26 operating system that came out in September, iOS 26.2 comes a little over a month after iOS 26.1 launched. ‌iOS 26‌.2 is compatible with the ‌iPhone‌ 11 series and later, as well as the second-generation ‌iPhone‌ SE. The new software can be downloaded on eligible iPhones over-the-air by going to Settings >...
iOS 26

iOS 26.2 Coming Soon With These 8 New Features on Your iPhone

Thursday December 11, 2025 8:49 am PST by
Apple seeded the second iOS 26.2 Release Candidate to developers earlier this week, meaning the update will be released to the general public very soon. Apple confirmed iOS 26.2 would be released in December, but it did not provide a specific date. We expect the update to be released by early next week. iOS 26.2 includes a handful of new features and changes on the iPhone, such as a new...
macOS Tahoe 26 Thumb

Apple Releases macOS Tahoe 26.2 With Edge Light

Friday December 12, 2025 10:08 am PST by
Apple today released macOS Tahoe 26.2, the second major update to the macOS Tahoe operating system that came out in September. macOS Tahoe 26.2 comes five weeks after Apple released macOS Tahoe 26.1. Mac users can download the macOS Tahoe update by using the Software Update section of System Settings. macOS Tahoe 26.2 includes Edge Light, a feature that illuminates your face with soft...
airpods max 2024 colors

AirPods Max 2 Likely to Offer These 10 New Features

Monday December 15, 2025 7:41 am PST by
Apple released the AirPods Max on December 15, 2020, meaning the over-ear headphones launched five years ago today. While the AirPods Max were updated with a USB-C port and new color options last year, followed by support for lossless audio and ultra-low latency audio this year, the headphones lack some of the features that have been introduced for newer generations of the regular AirPods and the ...

Top Rated Comments

mk313 Avatar
8 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
8 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
8 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
8 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
8 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
8 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)