Apple Xcode Integer Underflow Flaw Lets Crafted Archives Leak Memory and Crash Builds
Researchers disclosed an integer underflow in Apple's Mach-O archive parser that lets crafted static libraries crash Xcode builds or leak process memory.
SecureLayer7 disclosed an integer underflow in the mach_o::Archive::Entry::name() function in Apple's open-source dyld project, reported to Apple Product Security on May 23, 2026, with no public patch after more than 90 days. Crafted static archives (.a files) cause the parser's unsigned index to wrap to SIZE_MAX, producing SIGSEGV crashes in the ld-prime linker, out-of-bounds reads that may print adjacent memory to stderr, or SIGABRT in libtool and ranlib. The modern parser is used by ld-prime, the default linker for arm64, arm64e, and x86_64 since Xcode 15, while legacy ld-classic is unaffected. Crafted archives need only be processed, creating supply-chain risk via vendored SDKs, binary dependencies, and CI pipelines.