GHSA-25gq-j9jx-43pg Gitea: Release attachment extension allowlist bypass via web release edit form (variant of CVE-2025-68939)
SummaryThe web handler `EditReleasePost` (`routers/web/repo/release.go`) reads form fields with prefix `attachment-edit-{uuid}` into a `map[uuid]newName`, passes that map to `release_service.UpdateRelease`, which writes the new name to the database via `repo_model.UpdateAttachmentByUUID` WITHOUT calling `upload.Verify` against `setting.Repository.Release.AllowedTypes`. The parent CVE-2025-68939 fix (PR #32151) added the equivalent `upload.Verify` call on the API edit endpoints via `attachment_service.UpdateAttachment`. The web release edit path was not updated.A user with repository write permission can rename any existing release attachment to a name with a forbidden extension via the web release edit form, bypassing the operator-configured allowlist.DetailsVulnerable code`routers/web/repo/release.go:597` `EditReleasePost`:`services/release/release.go:321` -- the unvalidated write:No `upload.Verify(nil, newName, setting.Repository.Release.AllowedTypes)` before the database write.Comparison: the parent fix on the API path`routers/api/v1/repo/release_attachment.go:341` (patched in PR #32151):Delegates to:The API path goes through `attachment_service.UpdateAttachment` which calls `upload.Verify(nil, attach.Name, allowedTypes)`. The web path bypasses this entirely.Proof of ConceptTested live against:Gitea `v1.26.1` community edition, Linux amd64, SQLite, Go 1.26.2`app.ini` includes `[repository.release] ALLOWED_TYPES = .zip,.tar.gz`Two users: `admin` (superuser, created via `gitea admin user create --admin`), `bob` (regular, repo owner of `bob/test-repo`)**Step 1**: bob creates release v0.1 and uploads `innocent.zip` (allowlist compliant) via the API.**Step 2**: Sanity. The patched API edit endpoint rejects a rename to a forbidden extension.Response: `HTTP 422` -- "This file cannot be uploaded or modified due to a forbidden file extension or type." (parent CVE-2025-68939 fix in action).**Step 3**: The attack. The web release edit form does NOT enforce the allowlist.Response: `HTTP 303 -> /bob/test-repo/releases`. The form is accepted with no validation error.**Step 4**: Verify.Response includes `"name": "evil.exe"`. The download link `/attachments/<uuid>` now serves the file under the forbidden extension.A self contained Python PoC ships with this advisory: `GITEA-R007_release_edit_extension_bypass.py`. End to end run:[GITEA-R007_release_edit_extension_bypass.py](https://github.com/user-attachments/files/27739265/GITEA-R007_release_edit_extension_bypass.py)ImpactSame impact class as the parent CVE-2025-68939 (HIGH, CVSS 8.2):Pre-condition: operator has set `Repository.Release.AllowedTypes` to a non-empty allowlist (a reasonable hardening posture when restricting release uploads).Threat actor: user holding repository write permission. In most Gitea deployments this is the repo owner, organization members, or invited collaborators.Effect: bypass the allowlist; an attachment uploaded under an allowed extension is renamed to a forbidden extension (.exe, .html, .svg, .js, ...) and served by Gitea under that name.Practical impact:Distribute malware files (e.g., `.exe`, `.dmg`, `.msi`, `.apk`) masquerading as a tagged release attachmentIf Gitea serves attachments with inline rendering (HTML, SVG), the renamed file hosts stored XSS against the Gitea originOperator hardening intent (the allowlist) is silently defeated, with no audit trail beyond the regular release-edit eventSuggested remediationMirror the parent CVE-2025-68939 fix into the web release edit path. In `services/release/release.go UpdateRelease`, verify each new name against the configured allowlist before persisting:The web handler `EditReleasePost` should map `IsErrFileTypeForbidden` to a 422 response (or equivalent flash error and form re-render) to match the API behavior.Alternative: refactor `attachment_service.UpdateAttachment` to accept a UUID (or expose a `UpdateAttachmentByUUID` variant in the service layer) and have the release service call that instead of the raw model function.Workaround for operators (no Gitea change required)Until a patched release lands, operators can mitigate by either:Removing the `Repository.Release.AllowedTypes` allowlist (accept any extension) -- this eliminates the bypass but also removes the defense, so it is only a holding move.Putting Gitea behind a reverse proxy that rewrites or strips suspicious `attachment-edit-*` form fields on POST to `/<owner>/<repo>/releases/edit/*` -- viable but operationally fragile.Restricting who has Write permission on repositories with a configured release allowlist -- in single-tenant deployments this may be acceptable.A vendor patch is the right answer; the workarounds above are stopgaps.CreditJose Rivas (bl4cksku111.com)ReferencesParent advisory: https://github.com/advisories/GHSA-263q-5cv3-xq9g (CVE-2025-68939)Parent fix: PR https://github.com/go-gitea/gitea/pull/32151 (commit `7adc4717ec`)CWE-424: https://cwe.mitre.org/data/definitions/424.htmlCWE-434: https://cwe.mitre.org/data/definitions/434.html
CVSS v3.1 score: 6.5