CVE-2026-50553

## Summary Note Mark validates book and note `slug` values with the OpenAPI/huma tag `pattern:"[a-z0-9-]+"`. huma compiles this with `regexp.MustCompile(s.Pattern)` and tests it with `patternRe.MatchString(str)`, an UNANCHORED match. Because the pattern is not anchored (`^...$`), any string that merely CONTAINS one `[a-z0-9-]` substring passes validation. A slug such as `../../../../../../tmp/escape` is accepted and stored verbatim. The data-export CLI commands (`note-mark migrate export` and `note-mark migrate export-v1`) join these unsanitized slugs straight into the output path with `path.Join` / `filepath.Join`, then `os.MkdirAll` the directory and `os.Create` the note file. `path.Join` resolves the `../` segments, so the note content file is written OUTSIDE the configured export directory. The export process commonly runs as root (default in Docker / bare-metal admin usage), so this is a root-privilege arbitrary directory create + file write. This is the unguarded sibling of GHSA-g49p-4qxj-88v3 (CVE class CWE-22 in the same export sinks). That fix added `filepath.Base(asset.Name)` to sanitize the asset filename, but the adjacent path components `book.Slug` and `note.Slug` — used in the very same `path.Join` calls in the same two export functions — were left raw, and their input-side `pattern` guard is bypassable as shown above. ## Vulnerable code Slug input validation (`backend/db/types.go`, v0.19.4): ```go type CreateBook struct { Name string `json:"name" required:"true" minLength:"1" maxLength:"80"` Slug string `json:"slug" required:"true" minLength:"1" maxLength:"80" pattern:"[a-z0-9-]+"` IsPublic bool `json:"isPublic,omitempty" default:"false"` } type CreateNote struct { Name string `json:"name" required:"true" minLength:"1" maxLength:"80"` Slug string `json:"slug" required:"true" minLength:"1" maxLength:"80" pattern:"[a-z0-9-]+"` } ``` huma applies the pattern UNANCHORED (`github.com/danielgtaylor/huma/[email protected]`): ```go // schema.