{"id":"CVE-2026-42590","aliases":["GHSA-7v3r-m9c8-r855","GO-2026-5234"],"url":"https://o3.security/vulnerability/CVE-2026-42590","summary":"Gotenberg: ExifTool group-prefix syntax bypasses dangerous-tag blocklist","details":"Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.30.0, The ExifTool metadata write blocklist in Gotenberg can be bypassed using ExifTool's group-prefix syntax, enabling arbitrary file rename, move, hardlink, and symlink creation on the server. ExifTool supports group-prefix syntax where File:FileName is processed identically to FileName -- the prefix is stripped by SetNewValue in Writer.pl before tag matching. The safeKeyPattern regex (^[a-zA-Z0-9\\-_.:]+$) allows colons, so prefixed tag names pass validation. Any prefix works: File:FileName, System:Directory, a:HardLink, etc. Additionally, FilePermissions, FileUserID, and FileGroupID pseudo-tags are not blocked at all and can modify file attributes without any prefix. This vulnerability is fixed in 8.30.0.","published":"2026-05-14T15:36:30.386Z","modified":"2026-08-07T11:48:56.124245478Z","cvss":{"score":8.2,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/gotenberg/gotenberg/v8","fixedVersion":null}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42590.json"},{"type":"ADVISORY","url":"https://github.com/gotenberg/gotenberg/security/advisories/GHSA-7v3r-m9c8-r855"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-42590"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:48:56.124245478Z"}}