diff --git a/src/lib/contentDisposition.test.ts b/src/lib/contentDisposition.test.ts
new file mode 100644
index 0000000..bf0dbc7
--- /dev/null
+++ b/src/lib/contentDisposition.test.ts
@@ -0,0 +1,17 @@
+import { describe, expect, it } from "vitest";
+import { attachmentDisposition } from "./contentDisposition.js";
+
+describe("attachmentDisposition", () => {
+  it("escapes quotes and semicolons", () => {
+    const h = attachmentDisposition('a"b;c.pdf');
+    expect(h).toBe(`attachment; filename="a_b_c.pdf"; filename*=UTF-8''a%22b%3Bc.pdf`);
+  });
+  it("encodes non-ASCII names", () => {
+    const h = attachmentDisposition("résumé.pdf");
+    expect(h).toContain('filename="r_sum_.pdf"');
+    expect(h).toContain("filename*=UTF-8''r%C3%A9sum%C3%A9.pdf");
+  });
+  it("strips CR/LF", () => {
+    expect(attachmentDisposition("a\r\nb.txt")).not.toMatch(/[\r\n]/);
+  });
+});
diff --git a/src/lib/contentDisposition.ts b/src/lib/contentDisposition.ts
new file mode 100644
index 0000000..9a5f4fb
--- /dev/null
+++ b/src/lib/contentDisposition.ts
@@ -0,0 +1,14 @@
+/**
+ * Build an RFC 6266 attachment Content-Disposition header (#61): an ASCII
+ * fallback in `filename` and the percent-encoded UTF-8 name in `filename*`.
+ */
+export function attachmentDisposition(filename: string): string {
+  const clean = filename.replace(/[\r\n\u0000-\u001f\u007f]/g, "");
+  const fallback =
+    clean.replace(/[^\x20-\x7e]/g, "_").replace(/["\;%]/g, "_").trim() || "download";
+  const encoded = encodeURIComponent(clean || "download").replace(
+    /['()*]/g,
+    (c) => `%${c.charCodeAt(0).toString(16).toUpperCase()}`,
+  );
+  return `attachment; filename="${fallback}"; filename*=UTF-8''${encoded}`;
+}
diff --git a/src/lib/priceValidation.test.ts b/src/lib/priceValidation.test.ts
new file mode 100644
index 0000000..15a76c7
--- /dev/null
+++ b/src/lib/priceValidation.test.ts
@@ -0,0 +1,11 @@
+import { describe, expect, it } from "vitest";
+import { priceSchema } from "./priceValidation.js";
+
+describe("priceSchema", () => {
+  it.each(["1", "0.50", "12.1234567", "0.0000001"])("accepts %s", (v) => {
+    expect(priceSchema.safeParse(v).success).toBe(true);
+  });
+  it.each(["abc", "-1", "0", "0.0", "1.23456789", "", "1e3", " 1", "1."])("rejects %s", (v) => {
+    expect(priceSchema.safeParse(v).success).toBe(false);
+  });
+});
diff --git a/src/lib/priceValidation.ts b/src/lib/priceValidation.ts
new file mode 100644
index 0000000..455d2e3
--- /dev/null
+++ b/src/lib/priceValidation.ts
@@ -0,0 +1,11 @@
+import { z } from "zod/v4";
+import { usdcToStroops } from "../utils/usdc.js";
+
+/** Zod string for a positive USDC price with at most 7 decimals. */
+export const priceSchema = z.string().refine((v) => {
+  try {
+    return usdcToStroops(v) > 0n;
+  } catch {
+    return false;
+  }
+}, "must be a positive decimal number with at most 7 decimal places");
diff --git a/src/lib/stellarAddressValidation.test.ts b/src/lib/stellarAddressValidation.test.ts
new file mode 100644
index 0000000..d0fa355
--- /dev/null
+++ b/src/lib/stellarAddressValidation.test.ts
@@ -0,0 +1,14 @@
+import { describe, expect, it } from "vitest";
+import { Keypair } from "@stellar/stellar-sdk";
+import { stellarAddressSchema } from "./stellarAddressValidation.js";
+
+describe("stellarAddressSchema", () => {
+  it("accepts a valid address", () => {
+    expect(stellarAddressSchema.safeParse(Keypair.random().publicKey()).success).toBe(true);
+  });
+  it("rejects malformed values", () => {
+    expect(stellarAddressSchema.safeParse("G" + "A".repeat(55)).success).toBe(false);
+    expect(stellarAddressSchema.safeParse("abc").success).toBe(false);
+    expect(stellarAddressSchema.safeParse("").success).toBe(false);
+  });
+});
diff --git a/src/lib/stellarAddressValidation.ts b/src/lib/stellarAddressValidation.ts
new file mode 100644
index 0000000..7aa52dc
--- /dev/null
+++ b/src/lib/stellarAddressValidation.ts
@@ -0,0 +1,7 @@
+import { z } from "zod/v4";
+import { StrKey } from "@stellar/stellar-sdk";
+
+/** Zod string that must be a valid Stellar ed25519 public key (G...). */
+export const stellarAddressSchema = z
+  .string()
+  .refine((v) => StrKey.isValidEd25519PublicKey(v), "must be a valid Stellar public key (G..., 56 chars)");
diff --git a/src/lib/textUploadValidation.test.ts b/src/lib/textUploadValidation.test.ts
new file mode 100644
index 0000000..4864c77
--- /dev/null
+++ b/src/lib/textUploadValidation.test.ts
@@ -0,0 +1,16 @@
+import { describe, expect, it } from "vitest";
+import { validateTextContent } from "./textUploadValidation.js";
+
+describe("validateTextContent", () => {
+  it("accepts plain text and markdown", () => {
+    expect(validateTextContent(Buffer.from("# Title\n\nHello 1 < 2 and 3 > 2"))).toBeNull();
+  });
+  it("rejects HTML", () => {
+    expect(validateTextContent(Buffer.from("<html><body>x</body></html>"))).not.toBeNull();
+    expect(validateTextContent(Buffer.from("hi <script>alert(1)</script>"))).not.toBeNull();
+  });
+  it("rejects invalid UTF-8 and NUL bytes", () => {
+    expect(validateTextContent(Buffer.from([0xff, 0xfe, 0xfd]))).not.toBeNull();
+    expect(validateTextContent(Buffer.from("a\u0000b"))).not.toBeNull();
+  });
+});
diff --git a/src/lib/textUploadValidation.ts b/src/lib/textUploadValidation.ts
new file mode 100644
index 0000000..d597e16
--- /dev/null
+++ b/src/lib/textUploadValidation.ts
@@ -0,0 +1,28 @@
+/**
+ * Validation for text/* uploads (#62): content must be valid UTF-8, free of
+ * NUL bytes, and must not look like HTML/SVG/script markup.
+ */
+
+const MARKUP_PATTERN =
+  /<\s*(!doctype\s+html|html|head|body|script|iframe|object|embed|svg|style|link|meta|img|form|a\s)\b|<\s*\?xml|javascript:/i;
+
+export function isTextMimeType(mime: string): boolean {
+  return mime.startsWith("text/");
+}
+
+/** Returns an error message when the buffer is not acceptable text, else null. */
+export function validateTextContent(buffer: Buffer): string | null {
+  let text: string;
+  try {
+    text = new TextDecoder("utf-8", { fatal: true }).decode(buffer);
+  } catch {
+    return "Text uploads must be valid UTF-8";
+  }
+  if (text.includes("\u0000")) {
+    return "Text uploads must not contain binary data";
+  }
+  if (MARKUP_PATTERN.test(text)) {
+    return "Text uploads must not contain HTML or script markup";
+  }
+  return null;
+}
diff --git a/src/lib/uploadValidation.ts b/src/lib/uploadValidation.ts
index be8af3d..31a5889 100644
--- a/src/lib/uploadValidation.ts
+++ b/src/lib/uploadValidation.ts
@@ -1,3 +1,5 @@
+import { isTextMimeType, validateTextContent } from "./textUploadValidation.js";
+
 /**
  * Upload guardrails (#87): content-type allowlist and declared-vs-detected
  * content-type validation.
@@ -150,5 +152,10 @@ export function validateUpload(
     };
   }
 
+  if (isTextMimeType(declared)) {
+    const textError = validateTextContent(buffer);
+    if (textError) return { ok: false, status: 415, error: textError };
+  }
+
   return { ok: true, contentType: declared };
 }
diff --git a/src/routes/resources.ts b/src/routes/resources.ts
index 177c405..a461e81 100644
--- a/src/routes/resources.ts
+++ b/src/routes/resources.ts
@@ -1,4 +1,5 @@
 import { Router, type Router as RouterType } from "express";
+import { attachmentDisposition } from "../lib/contentDisposition.js";
 import { promises as fs } from "node:fs";
 import { apiKeyAuth } from "../middleware/apiKeyAuth.js";
 import { requestSignatureAuth } from "../middleware/requestSignatureAuth.js";
@@ -392,10 +393,8 @@ router.get("/resources/:id", dynamicPaywall, async (req, res) => {
 
   const { buffer, mimeType } = fileContent;
   res.setHeader("Content-Type", mimeType);
-  res.setHeader(
-    "Content-Disposition",
-    `attachment; filename="${resource.storagePath.split("/").pop()}"`,
-  );
+  res.setHeader("X-Content-Type-Options", "nosniff");
+  res.setHeader("Content-Disposition", attachmentDisposition(resource.storagePath.split("/").pop() ?? ""));
   res.send(buffer);
 });
 
diff --git a/src/schemas/requests.ts b/src/schemas/requests.ts
index d309347..9a53e2d 100644
--- a/src/schemas/requests.ts
+++ b/src/schemas/requests.ts
@@ -1,12 +1,14 @@
 import { z } from "zod/v4";
 import { config } from "../config.js";
+import { stellarAddressSchema } from "../lib/stellarAddressValidation.js";
+import { priceSchema } from "../lib/priceValidation.js";
 import { webhookEventValues } from "./webhooks.js";
 
 export const publisherRegisterSchema = z
   .object({
     name: z.string().min(1),
     email: z.email(),
-    walletAddress: z.string().min(1),
+    walletAddress: stellarAddressSchema,
   })
   .strict();
 
@@ -14,8 +16,8 @@ export const linkPublishSchema = z
   .object({
     title: z.string().min(1),
     description: z.string().optional(),
-    price: z.string().min(1),
-    walletAddress: z.string().optional(),
+    price: priceSchema,
+    walletAddress: stellarAddressSchema.optional(),
     externalUrl: z.url(),
   })
   .strict();
@@ -23,9 +25,9 @@ export const linkPublishSchema = z
 export const filePublishBodySchema = z
   .object({
     title: z.string().min(1),
-    price: z.string().min(1),
+    price: priceSchema,
     description: z.string().optional(),
-    walletAddress: z.string().optional(),
+    walletAddress: stellarAddressSchema.optional(),
   })
   .strict();
 
@@ -44,27 +46,27 @@ export const registerResourceSchema = z
 
 export const preparePriceSchema = z
   .object({
-    price: z.string().min(1),
+    price: priceSchema,
   })
   .strict();
 
 export const setPriceSchema = z
   .object({
     signedXdr: z.string().min(1),
-    price: z.string().min(1),
+    price: priceSchema,
   })
   .strict();
 
 export const prepareOwnershipSchema = z
   .object({
-    newCreator: z.string().min(1),
+    newCreator: stellarAddressSchema,
   })
   .strict();
 
 export const transferOwnershipSchema = z
   .object({
     signedXdr: z.string().min(1),
-    newCreator: z.string().min(1),
+    newCreator: stellarAddressSchema,
   })
   .strict();