Apple dyld user-mode PAC bypass and memory corruption
CVE-2026-20700 is a memory corruption vulnerability in Apple’s dyld dynamic linker. Apple states the issue was addressed through improved state management. The vendor advisory says an attacker with memory write capability may be able to execute arbitrary code. Multiple supporting reports further characterize the flaw as a user-mode Pointer Authentication Code (PAC) bypass in dyld that was used as part of the DarkSword iOS exploit chain, where it was chained after initial JavaScriptCore code execution to bypass user-mode PAC protections and enable subsequent exploit stages. Apple reported that the issue may have been exploited in an extremely sophisticated attack against specific targeted individuals on versions of iOS before iOS 26. The vulnerability was fixed in iOS 26.3, iPadOS 26.3, macOS Tahoe 26.3, tvOS 26.3, visionOS 26.3, and watchOS 26.3.
Are you exposed to this one?
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos (4 hidden).
This repository is a standalone iOS/macOS research PoC for a dyld chained-fixup/page-in-linking attack surface associated with CVE-2026-20700, not a framework module. Its purpose is to demonstrate that dyld can be coerced into producing PAC-valid function pointers and writing them into attacker-chosen slots inside a crafted Mach-O dylib, then show those pointers being executed through normal control flow. Structure: the Makefile orchestrates the full pipeline; src/launcher.c is the main iOS launcher; generators/gen_exports.py creates exports.c with ~N dummy exported symbols; generators/gen_client.py creates client.c with ~N imports and also emits a simple generated launcher variant used to stress dyld with a small-stack dlopen path; generators/gen_malformed_dylib.py is the core exploit generator that builds libmalformed.dylib byte-by-byte with custom LC_DYLD_CHAINED_FIXUPS metadata and malformed/controlled chain data; tools/inspect_fixups.py parses LC_DYLD_CHAINED_FIXUPS for sanity checking; tools/scan_pointers.py inspects Mach-O pointer sections; blog/ contains detailed English and Italian write-ups. Main exploit capabilities: (1) generate a malformed Mach-O dylib whose chained fixups cause dyld to resolve imported symbols and write PAC-valid pointers into selected __DATA offsets such as +0x10 and optionally +0x20; (2) validate the primitive using canaries in the malformed dylib's __DATA; (3) directly call the dyld-written function pointer or, in chain_close mode, register the second written pointer as a dispatch_source_t timer callback so the event loop invokes attacker_hook naturally; (4) stress dyld page-in linking using a second dylib with ~99k imports and a small-stack worker thread; and (5) trigger deterministic crash/reachability behavior in malformed page-in processing for research. The launcher coordinates two threads: Thread A loads libexports.dylib, resolves write_target_value, loads Frameworks/libmalformed.dylib, locates its __DATA via dyld image APIs, and checks whether dyld wrote the expected PAC-valid pointer into the target slot. In chain_close mode it also uses the second slot as a dispatch callback target. Thread B uses a constrained stack and deep recursion before dlopen("@executable_path/libclient.dylib") to exercise the dyld gate/path under stress. The Makefile presets (stress, exploit, chain_close) switch between crash proof, stable intra-image write primitive, and dispatch-based execution demo. No network C2 or remote endpointing is present. The observable endpoints are local Mach-O paths, bundle/package artifacts, and signing/provisioning files. The repository is a real exploit/research PoC rather than a detector: it builds runnable binaries and a crafted dylib to demonstrate a local code-execution-enabling primitive on iOS/arm64e systems.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
155 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A dyld arbitrary code execution vulnerability affecting multiple Apple platforms that Apple says was used in highly sophisticated targeted attacks.
One of six CVEs in the DarkSword iOS exploit chain affecting older iOS 18 devices and tracked by CISA as actively exploited.
One of six vulnerabilities leveraged by the DarkSword exploit kit targeting iPhones and iPads running iOS 18.x; significant because DarkSword is described as actively exploited and broadly deployed.
One of six iOS vulnerabilities used by the DarkSword exploit kit to target iPhones running iOS 18.4 through 18.7; Apple shipped fixes in security updates and later expanded iOS 18.7.7 availability to protect more devices.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.