GHSA-3fwp-p5rj-2pxf Gitea: Missing repository-unit authorization on issue-template API endpoints

• Go code.gitea.io/gitea: < 1.26.2 → fixed in 1.26.2

Summary Three Gitea API endpoints — `GET /repos/{owner}/{repo}/issue_templates`, `GET /repos/{owner}/{repo}/issue_config` and `GET /repos/{owner}/{repo}/issue_config/validate` — read files from the repository's Code default branch (`.gitea/ISSUE_TEMPLATE/*` and `issue_config.yaml`) and return their contents, but are registered without the `reqRepoReader(unit.TypeCode)` authorization middleware that every sibling Code-tree endpoint in the same route group carries. A user who has access to a private repository through *any single repository unit* (for example an organization team granted only the Issues unit, with no Code access) can therefore read the issue-template and issue-config files of that repository's Code tree, which their permission set should not expose. --- Root cause The three endpoints lack the unit guard `routers/api/v1/api.go:1433-1437`: m.Get("/issue_templates", context.ReferencesGitRepo(), repo.GetIssueTemplates) m.Get("/issue_config", context.ReferencesGitRepo(), repo.GetIssueConfig) m.Get("/issue_config/validate", context.ReferencesGitRepo(), repo.ValidateIssueConfig) m.Get("/languages", reqRepoReader(unit.TypeCode), repo.GetLanguages) m.Get("/licenses", reqRepoReader(unit.TypeCode), repo.GetLicenses) `context.ReferencesGitRepo()` only opens the git repository — it performs no permission check. Every other endpoint in this group that reads Code-tree content is guarded with `reqRepoReader(unit.TypeCode)`: `/languages`, `/licenses`, `/contents/*`, `/file-contents`, and `/{ball_type:tarball|zipball|bundle}/*` (api.go:1418-1445). The three issue-template endpoints are the only Code-tree readers in the group missing that guard. The enclosing group runs `repoAssignment()` (api.go:1446), whose access check is satisfied by `HasAnyUnitAccessOrPublicAccess` — i.e. access to any unit of the repository is sufficient to pass. Without a per-unit `reqRepoReader`, the handlers run for a caller who has no Code permission. The handlers return Code-tree file contents `routers/api/v1/repo/repo.go`: func GetIssueTemplates(ctx *context.APIContext) { // :1179 ret := issue.ParseTemplatesFromDefaultBranch(ctx.Repo.Repository, ctx.Repo.GitRepo) ... ctx.JSON(http.StatusOK, ret.IssueTemplates) } func GetIssueConfig(ctx *context.APIContext) { // :1209 issueConfig, _ := issue.GetTemplateConfigFromDefaultBranch(ctx.Repo.Repository, ctx.Repo.GitRepo) ctx.JSON(http.StatusOK, issueConfig) } `ParseTemplatesFromDefaultBranch` / `GetTemplateConfigFromDefaultBranch` read `.gitea/ISSUE_TEMPLATE/*` and `issue_config.yaml` from the default (Code) branch and return them in the JSON response. --- Proof of Concept `victim-org/private-repo` is a private repository. The attacker is a member of an organization team granted access to that repository through a non-Code unit only (e.g. the Issues unit) — a supported Gitea permission configuration. GET /api/v1/repos/victim-org/private-repo/issue_templates HTTP/1.1 Host: TARGET Authorization: token The response is `200 OK` with the parsed contents of the repository's `.gitea/ISSUE_TEMPLATE/*` files. The same applies to `/issue_config`. Because the caller lacks the Code unit, every other Code-tree endpoint (`/contents`, `/languages`, …) correctly returns `404`/`403` for the same token — only these three return data. --- Impact A repository collaborator whose granted permissions exclude the Code unit can read the issue-template and issue-config files from the Code default branch of a private repository. The exposure is limited to those specific configuration files (not arbitrary Code-tree content), which is why this is rated low impact. It is nonetheless a unit-level authorization bypass: the endpoints disclose Code-unit content to callers the permission model is meant to exclude. --- Suggested fix Add the same unit guard the sibling endpoints use, in `routers/api/v1/api.go`: m.Get("/issue_templates", reqRepoReader(unit.TypeCode), context.ReferencesGitRepo(), repo.GetIssueTemplates) m.Get("/issue_config", reqRepoReader(unit.TypeCode), context.ReferencesGitRepo(), repo.GetIssueConfig) m.Get("/issue_config/validate", reqRepoReader(unit.TypeCode), context.ReferencesGitRepo(), repo.ValidateIssueConfig) (If issue templates are intended to be visible to Issues-unit users for issue creation, `reqRepoReader(unit.TypeIssues)` is the appropriate guard — but the current absence of any unit guard is the bug.) --- References • CWE-862 Missing Authorization • CWE-284 Improper Access Control • OWASP A01:2021 Broken Access Control