This update for libX11 and libxcb fixes the following issue: libX11: These security issues were fixed: - CVE-2018-14599: The function XListExtensions was vulnerable to an off-by-one error caused by malicious server responses, leading to DoS or possibly unspecified other impact . - CVE-2018-14600: The function XListExtensions interpreted a variable as signed instead of unsigned, resulting in an out-of-bounds write , leading to DoS or remote code execution . - CVE-2018-14598: A malicious server could have sent a reply in which the first string overflows, causing a variable to be set to NULL that will be freed later on, leading to DoS . This non-security issue was fixed: - Make use of the new 64-bit sequence number API in XCB 1.11.1 to avoid the 32-bit sequence number wrap in libX11 . libxcb: - Expose 64-bit sequence number from XCB API so that Xlib and others can use it even on 32-bit environment