CVE-2017-18269: GNU Glibc

Critical severity, CVSS 9.8. EPSS: 4.6% chance of exploitation in the next 30 days.

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.

Affected products

• GNU Glibc: from 2.21, up to and including 2.27

Published 2018-05-18. Last modified 2026-06-17.