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Researchers reported that Apple’s fix for CVE-2021-30724 in the root-privileged CVMServer daemon introduced a new flaw, tracked as CVE-2022-26721, that could be reached from the Safari renderer sandbox on macOS. The bug stemmed from uninitialized cleanup metadata left behind when a bounds check aborted processing, creating a path for attacker-controlled munmap operations on arbitrary memory pages inside the service.
Theori showed the issue could be turned into root code execution by shaping heap contents, using a binary-search-style oracle to infer CVMServer memory layout, and overwriting dyld private-memory function pointers. A proof of concept reportedly read /var/db/SystemKey, which can be used to decrypt macOS keychain files, underscoring the impact of the sandbox escape and privilege-escalation chain. Apple addressed the vulnerability in macOS 12.4 by replacing malloc with calloc to ensure the descriptor buffer was zero-initialized.
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4 events from the most recent confirmed update back to the earliest known activity.
Theori stated that Apple fixed CVE-2022-26721 in macOS 12.4 by replacing malloc with calloc to zero-initialize the descriptor buffer. This addressed the uninitialized memory condition in CVMServer.
Theori reported that Apple’s patch for CVE-2021-30724 introduced CVE-2022-26721, an uninitialized memory flaw in the root-privileged CVMServer daemon on macOS. The bug left cleanup metadata uninitialized when a bounds check triggered a break, enabling attacker-controlled munmap calls on arbitrary memory pages.
On June 16, 2022, Theori published technical analysis showing how CVE-2022-26721 could be exploited from the Safari renderer sandbox to achieve root code execution. The proof of concept demonstrated reading /var/db/SystemKey, which could be used to decrypt macOS keychain files.
Trend Micro reported CVE-2021-30724, a CVMServer vulnerability affecting macOS and iOS, in research published on June 3, 2021. The later Theori analysis states Apple’s fix for this issue introduced a new bug.
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Apple disclosed two high-severity macOS vulnerabilities, **CVE-2026-28891** and **CVE-2026-28817**, that could allow an application or sandboxed process to escape sandbox restrictions. Both flaws were attributed to race conditions, classified as **CWE-362**, and carried the same `CVSS v3.1` vector: `AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H`, indicating local exploitation with potentially severe impact to confidentiality, integrity, and availability. Apple said the issues were remediated through **additional validation** and **improved state handling**. Fixes were released for **macOS Sequoia 15.7.5**, **macOS Sonoma 14.8.5**, and **macOS Tahoe 26.4**, and organizations running affected macOS systems should prioritize those updates because successful exploitation could let untrusted code break out of the sandbox and operate with broader system access.
Jun 29, 2026
A technical review of **CVE-2018-4340** detailed how a Safari sandbox escape on macOS abused the `MediaRemote` framework and the `com.apple.mediaremoted.xpc` service to trigger the launch of arbitrary installed applications. The researcher said Safari could reach the Mach service and spoof a bundle identifier inside an `MRNowPlayingPlayerPathProtobuf` message, leading `mediaremoted` to invoke LaunchServices and open apps such as Calculator. The write-up said Apple later fully patched the MediaRemote issue after it was publicly presented. The same research also described a separate Safari-reachable XPC service, `com.apple.hiservices-xpcservice`, that allegedly exposed methods capable of rebooting the system, reading arbitrary plist files, and revealing remote files in Finder. The author linked that behavior to an older **macOS Gatekeeper bypass** involving NFS shares, raising the possibility that a remotely hosted application could be registered with LaunchServices and then launched through the MediaRemote path, extending the impact from sandbox escape to potential Gatekeeper circumvention.
Aug 1, 2026
Researchers disclosed the first public bypass of Apple **Memory Integrity Enforcement (MIE)** on macOS 26.4.1 by chaining two vulnerabilities: `CVE-2026-64704` in **SMBClient** and `CVE-2026-64699` in **webdavfs**. The SMB flaw is a type confusion issue triggered when a macOS client connects to a malicious SMB server, causing the kernel to reinterpret a Resolve ID context as a lease context and misuse attacker-influenced kernel pointers. The WebDAV flaw is a kernel memory disclosure bug triggered by a crafted HTTP `206` response from a malicious WebDAV server, leaking uninitialized kernel memory to userspace. The researchers said the combined exploit chain produces arbitrary kernel read/write primitives and ultimately kernel code execution, allowing an unprivileged user to escalate privileges to **root** despite Apple’s layered kernel protections. Apple has patched both issues in macOS 26.6, and the disclosure was accompanied by a public exploit-development challenge and notice of a planned Black Hat USA presentation detailing the technique.
Jul 30, 2026