{"id":"ALPINE-CVE-2026-48104","details":"7-Zip is a file archiver with a high compression ratio. Versions 9.18 through 26.00 contain an uninitialized heap read in the SquashFS archive handler caused by a sparsely populated index array. In the SquashFS handler, _blockToNode is allocated with capacity for every metadata block but populated only when an inode crosses a block boundary, so a crafted image with few inodes spanning many blocks leaves most slots holding raw heap contents (the underlying allocator does not zero-initialize POD storage). When OpenDir looks up an attacker-influenced blockIndex (derived from the RootInode superblock field), it reads two of these uninitialized slots and passes them as the left/right bounds of a binary search over _nodesPos, which dereferences the midpoint without bounds checking; if the resulting value happens to match the search key, the returned index is used to read a full node struct from _nodes whose fields feed further directory parsing, forming a chained OOB read primitive that is heap-layout-dependent and not reliably triggerable. The SquashFS handler is enabled by default in stock 7z.dll and the issue triggers during Open() with no interaction beyond opening the file; impact is denial of service from wild-pointer dereference and potential heap information disclosure, with no write primitive. Version 26.01 fixes the issue.","modified":"2026-09-14T16:18:08.207487212Z","published":"2026-06-05T17:16:48.547Z","upstream":["CVE-2026-48104"],"references":[{"type":"ADVISORY","url":"https://security.alpinelinux.org/vuln/CVE-2026-48104"}],"affected":[{"package":{"name":"7zip","ecosystem":"Alpine:v3.24","purl":"pkg:apk/alpine/7zip?arch=source"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"26.01-r0"}]}],"ecosystem_specific":{},"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/alpine/ALPINE-CVE-2026-48104.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:N/A:L"}]}