{"id":"CVE-2026-117556","aliases":[],"title":"zchunk before 1.5.5 Heap Out-of-Bounds Read via read_preface()","description":"zchunk before 1.5.5 contains a heap out-of-bounds read vulnerability in read_preface() in src/lib/header.c that passes the total header length instead of remaining bytes to compint parsing functions. Attackers can supply a crafted .zck file whose header ends inside a compressed integer, causing reads past the heap header buffer and crashing the application.","severity":"medium","score":5.3,"published":"2026-10-27T13:07:51.708Z","modified":"2026-10-27T13:07:51.708Z","withdrawn":false,"knownExploited":false,"affected":[],"references":["https://github.com/zchunk/zchunk/issues/119","https://github.com/zchunk/zchunk","https://github.com/zchunk/zchunk/commit/02b371a64bf98245df97315d07c684a0ca5ea1df","https://github.com/zchunk/zchunk/releases/tag/1.5.5","https://github.com/zchunk/zchunk/blob/1.5.4/src/lib/header.c#L167","https://www.vulncheck.com/advisories/zchunk-before-1.5.5-heap-out-of-bounds-read-via-read-preface"],"sources":[{"name":"CVE","id":"CVE-2026-117556","modified":"2026-10-27T13:07:51.708Z","url":"https://www.cve.org/CVERecord?id=CVE-2026-117556"}],"assessments":[{"source":"CNA","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","score":5.3},{"source":"CNA","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L","score":4.3}]}