Go · gogs.io/gogs
Gogs Missing Authorization in Attachment Download
In Gogs 0.14.1, GET /attachments/:uuid returns the raw attachment file without verifying whether the requester has view permission for the associated Issue/Comment/Release or the repository.
In a test environment with REQUIRE_SIGNIN_VIEW = false, we confirmed that an unauthenticated user can download attachments belonging to a private repository.
/attachments/:uuid retrieves an attachment record solely by the UUID provided in the URL and returns the corresponding local file without performing any authorization checks against the attachment’s parent object (Issue/Comment/Release) or the repository it belongs to. As a result, even attachments under private repositories can be downloaded by an unauthenticated user (or a user without proper permissions) as long as the UUID is known.
Relevant code (internal/cmd/web.go:306):
m.Get("/attachments/:uuid", func(c *context.Context) {
attach, err := database.GetAttachmentByUUID(c.Params(":uuid"))
if err != nil {
c.NotFoundOrError(err, "get attachment by UUID")
return
} else if !com.IsFile(attach.LocalPath()) {
c.NotFound()
return
}
fr, err := os.Open(attach.LocalPath())
if err != nil {
c.Error(err, "open attachment file")
return
}
defer fr.Close()
c.Header().Set("Content-Security-Policy", "default-src 'none'; style-src 'unsafe-inline'; sandbox")
c.Header().Set("Cache-Control", "public,max-age=86400")
c.Header().Set("Content-Disposition", fmt.Sprintf(`inline; filename="%s"`, attach.Name))
if _, err = io.Copy(c.Resp, fr); err != nil {
c.Error(err, "copy from file to response")
return
}
})
The UUID lookup itself also performs no validation tied to repository visibility or user permissions. Authorization is not enforced at this layer.
Relevant code (internal/database/attachment.go:124):
// GetAttachmentByUUID returns attachment by given UUID.
func GetAttachmentByUUID(uuid string) (*Attachment, error) {
return getAttachmentByUUID(x, uuid)
}
[auth] REQUIRE_SIGNIN_VIEW = false.REQUIRE_SIGNIN_VIEW = true, exploitation may still be possible because the handler does not check repository-level permissions; a user who can log in but lacks access to the target repository may still retrieve the attachment.myadmin/idor-attach-1770724346-1a13bb.f06d90f8-5b62-4c10-ac8d-f11fdf870b57).GET /attachments/<uuid> → the attachment file is successfully downloadedREQUIRE_SIGNIN_VIEW = false: none (works without authentication).REQUIRE_SIGNIN_VIEW = true: only the ability to log in (repository view permission is not required in practice).Confidential information attached to private repositories or restricted Issues/Releases may be disclosed.
While the severity depends on the attachment contents, attachments frequently contain sensitive data, making the potential impact high.
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Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.