Apple has released an out-of-band update for iOS and iPadOS, versions 26.4.2 and 18.7.8, respectively. It is intended to fix a vulnerability in Notification Services. The bug, CVE-2026-28950, caused deleted notifications to remain stored on the device. The FBI reportedly exploited this to recover Signal messages.
Apple describes the issue as follows: “Notifications marked for deletion might have been unexpectedly retained on the device.” The company has resolved the issue through improved data redaction, including the removal of existing cached copies, but provides no further technical details on how long data could remain on a device or how it could be recovered.
How the FBI Retrieved Signal Messages
The real reason behind the emergency update becomes clearer through reports elsewhere. These describe how the FBI managed to recover deleted Signal messages from a suspect’s iPhone. The recovered data came from iOS’s internal notification storage, not from Signal’s own encrypted message archive. According to court documents published by supporters of the suspects, the notifications were still present even after Signal had been completely removed from the device.
Signal has expressly thanked Apple for its swift response. The communications team states that this step demonstrates Apple’s understanding of the sensitivity of this issue as part of an “ecosystem designed to safeguard the fundamental human right to private communication.”
What can users do?
Users are advised to install iOS 26.4.2 as soon as possible via Settings > General > Software Update. Those still running iOS 18 can update to iOS 18.7.8. Apple has not confirmed whether the vulnerability was actively exploited, nor why the update was released outside the usual release cycle.
Those who want to be extra cautious can adjust the notification settings in Signal. Via Settings > Notifications > Notification Content, it is possible to limit the display to “Name Only” or “No Name or Content.” This prevents message content from appearing in the iOS notification storage at all.
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