CVE-2026-50105: Gitea RSS/Atom Feed Handlers Bypass API-token Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-6cqf-375w-639g",
  "modified" : "2026-07-21T20:40:24Z",
  "published" : "2026-07-21T20:40:24Z",
  "aliases" : [ "CVE-2026-50105" ],
  "summary" : "Gitea: RSS/Atom feed handlers bypass API-token scope & public-only confinement (incomplete fix of #37698)",
  "details" : "### Summary\n\nGitea's RSS/Atom feed handlers accept API-token Basic auth but perform **no token-scope or\npublic-only enforcement**. A personal access token that is correctly blocked (HTTP 403) from a\nprivate repository on `/raw`, `/media`, `/archive`, and `/releases/download/...` — because it is\nmarked *public-only* or lacks the `repository` scope category — still returns that repository's\nprivate content through the feed routes. This is a token-confinement bypass and appears to be an\nincomplete fix of #37698, which added that scope enforcement to the download handlers but not to the\nsibling feed handlers.\n\nThis is **not** a cross-user access bug: the requesting account must still legitimately have repo\nread access (`RepoAssignment` + `reqUnitCodeReader` are enforced). What is bypassed is the guarantee\nthat a *confined* token cannot reach private content — which is exactly the property #37698 was\nshipped to provide for downloads, and which matters when such a token is handed to a third-party\nservice/CI, leaked, or used in a lower-trust integration.\n\n### Details\n\n#37698 added `context.CheckTokenScopes` / `CheckRepoScopedToken`\n(`services/context/permission.go`) to the raw / media / archive / attachment download handlers, so a\npublic-only or wrong-scope-category token cannot read private-repo content even when the owning user\notherwise has access.\n\nThe feed handlers are registered with `webAuth.AllowBasic` (so they accept token Basic auth) but call\nno scope / public-only check. A grep for `CheckTokenScopes` / `CheckRepoScopedToken` / `IsApiToken`\nacross `routers/web/feed/` and the release feed handlers returns nothing.\n\nAffected routes (all token-reachable via `webAuth.AllowBasic`, none call the scope check):\n\n| Route | Handler | Private data exposed |\n|---|---|---|\n| `GET /{owner}/{repo}.rss` / `.atom` | `repo.Home` → `handleRepoHomeFeed` (`view_home.go`) | last-10 commits: SHA, full message, author name + email |\n| `GET /{owner}/{repo}/rss/branch/*`, `/atom/branch/*` | `feed.RenderBranchFeed*` → `ShowBranchFeed` (`routers/web/feed/branch.go`) | same commit data, any branch |\n| `GET /{owner}/{repo}/releases.rss` / `.atom` | `ReleasesFeedRSS/Atom` (`routers/web/repo/release.go`) → `ShowReleaseFeed` | private release names, notes, descriptions |\n| `GET /{owner}/{repo}/tags.rss` / `.atom` | `TagsListFeedRSS/Atom` → `ShowReleaseFeed` | private tag names + messages |\n| `GET /{user}.rss` / `.atom` | `showUserFeed` (`routers/web/feed/profile.go`), `includePrivate = self \\|\\| admin` | the token owner's private cross-repo activity stream |\n\nInconsistency that pins this down: the branch-feed routes sit in the **same route group** as `/raw`,\n`/media`, `/archive` (all of which call `checkDownloadTokenScope`), and `releases.rss` sits next to\n`/releases/attachments/{uuid}` and `/releases/download/...` (both go through `ServeAttachment` → scope\ncheck). Only the feeds were missed. The API equivalents (`ListReleases` / `ListTags`) are scope-gated\nvia `tokenRequiresScopes`.\n\nTwo distinct confinement bypasses:\n\n1. **Public-only bypass.** A token created with the *public-only* option is blocked (403) from a\n   private repo on `/raw`, `/archive`, `/releases/download/...`, but returns private commit / release\n   data via `.../releases.rss`, `.../rss/branch/*`, `/{owner}/{repo}.rss`, and the owner's private\n   activity via `/{user}.rss`.\n2. **Scope-category bypass.** A token scoped to only e.g. `read:issue` (no `read:repository`) is\n   rejected by the download handlers but reads repository commit/release content via the feeds.\n\n### PoC\n\nVerified live against the official `gitea/gitea:1.26.2` Docker image (sqlite, feeds enabled).\n\nSetup: non-admin user `alice`; private repo `alice/secret` with a commit\n`\"SECRET-COMMIT-MARKER ...\"` (file `secret.txt`) and a release `\"Private Release\"` / body\n`\"SECRET-RELEASE-MARKER ...\"`. Two confined personal access tokens, both sent via HTTP Basic so the\nauth method is identical across download and feed — only the route differs:\n- Token A: scopes `[\"public-only\", \"read:repository\"]`\n- Token B: scopes `[\"read:issue\"]`\n\n```bash\n# Token A — download is correctly blocked, feeds leak private content:\ncurl -u alice:$TOKEN_A https://<host>/alice/secret/raw/branch/main/secret.txt   # => 403  (fix works)\ncurl -u alice:$TOKEN_A https://<host>/alice/secret/rss/branch/main             # => 200, <title>SECRET-COMMIT-MARKER ...</title>\ncurl -u alice:$TOKEN_A https://<host>/alice/secret/releases.rss               # => 200, SECRET-RELEASE-MARKER ...\ncurl -u alice:$TOKEN_A \"https://<host>/alice.rss\"                             # => 200, private activity\n\n# Token B — wrong scope category, same split:\ncurl -u alice:$TOKEN_B https://<host>/alice/secret/raw/branch/main/secret.txt   # => 403\ncurl -u alice:$TOKEN_B https://<host>/alice/secret/rss/branch/main             # => 200, private commit leaked\n```\n\nAnonymous baseline returns 404 on the repo feeds (data is genuinely private) and a marker-free 200 on\n`/alice.rss` (public activity only) — confirming the leak is gated only by the missing token check.\n\n### Impact\n\nInformation disclosure of private **commit metadata** (SHA, message, author name+email),\n**release/tag notes**, and the owner's **private activity stream**, to the holder of a confined token\nthat was specifically configured *not* to reach private content. Not raw file blobs (feeds don't\nserve file contents). Requires a token belonging to an account that already has repo read access, so\nthe realistic threat is a leaked / shared / lower-trust token rather than an anonymous attacker —\nwhich is precisely the threat model #37698 addressed for downloads.\n\n### Suggested remediation\n\nAdd a token-scope check at the top of each feed handler, mirroring `checkDownloadTokenScope`:\n\n```go\nif context.CheckRepoScopedToken(ctx, ctx.Repo.Repository, auth_model.Read); ctx.Written() {\n    return\n}\n```\n\nfor `ShowBranchFeed`, `ShowRepoFeed`, `ShowFileFeed`, `ShowReleaseFeed` (repo feeds). For the user\nfeed, gate `includePrivate` behind a non-public-only token (or require the `user` / `repository`\nscope) so a confined token can't pull private activity.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "code.gitea.io/gitea"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.27.0"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/go-gitea/gitea/security/advisories/GHSA-6cqf-375w-639g"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/go-gitea/gitea"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/go-gitea/gitea/releases/tag/v1.27.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200", "CWE-862" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-07-21T20:40:24Z",
    "nvd_published_at" : null
  }
}