In the GNU C Library (aka glibc or libc6) before 2.28, parse_reg_exp in posix/regcomp.c misparses alternatives, which allows attackers to cause a denial of service (assertion failure and application exit) or trigger an incorrect result by attempting a regular-expression match.

In the GNU C Library (aka glibc or libc6) through 2.29, the memcmp function for the x32 architecture can incorrectly return zero (indicating that the inputs are equal) because the RDX most significant bit is mishandled.

In the GNU C Library (aka glibc or libc6) through 2.28, the getaddrinfo function would successfully parse a string that contained an IPv4 address followed by whitespace and arbitrary characters, which could lead applications to incorrectly assume that it had parsed a valid string, without the possibility of embedded HTTP headers or other potentially dangerous substrings.

The string component in the GNU C Library (aka glibc or libc6) through 2.28, when running on the x32 architecture, incorrectly attempts to use a 64-bit register for size_t in assembly codes, which can lead to a segmentation fault or possibly unspecified other impact, as demonstrated by a crash in __memmove_avx_unaligned_erms in sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S during a memcpy.

In the GNU C Library (aka glibc or libc6) through 2.28, attempting to resolve a crafted hostname via getaddrinfo() leads to the allocation of a socket descriptor that is not closed. This is related to the if_nametoindex() function.

stdlib/canonicalize.c in the GNU C Library (aka glibc or libc6) 2.27 and earlier, when processing very long pathname arguments to the realpath function, could encounter an integer overflow on 32-bit architectures, leading to a stack-based buffer overflow and, potentially, arbitrary code execution.

An SSE2-optimized memmove implementation for i386 in sysdeps/i386/i686/multiarch/memcpy-sse2-unaligned.S in the GNU C Library (aka glibc or libc6) 2.21 through 2.27 does not correctly perform the overlapping memory check if the source memory range spans the middle of the address space, resulting in corrupt data being produced by the copy operation. This may disclose information to context-dependent attackers, or result in a denial of service, or, possibly, code execution.

An AVX-512-optimized implementation of the mempcpy function in the GNU C Library (aka glibc or libc6) 2.27 and earlier may write data beyond the target buffer, leading to a buffer overflow in __mempcpy_avx512_no_vzeroupper.

The malloc implementation in the GNU C Library (aka glibc or libc6), from version 2.24 to 2.26 on powerpc, and only in version 2.26 on i386, did not properly handle malloc calls with arguments close to SIZE_MAX and could return a pointer to a heap region that is smaller than requested, eventually leading to heap corruption.

An integer overflow in the implementation of the posix_memalign in memalign functions in the GNU C Library (aka glibc or libc6) 2.26 and earlier could cause these functions to return a pointer to a heap area that is too small, potentially leading to heap corruption.