@@ -350,7 +350,13 @@ function processHeader (request, key, val) {
       } else if (typeof val[i] === 'object') {
         throw new InvalidArgumentError(`invalid ${key} header`)
       } else {
-        arr.push(`${val[i]}`)
+        // Coerce primitives (and reject unsafe coercions such as functions
+        // with a crafted toString/Symbol.toPrimitive).
+        const str = `${val[i]}`
+        if (!isValidHeaderValue(str)) {
+          throw new InvalidArgumentError(`invalid ${key} header`)
+        }
+        arr.push(str)
       }
     }
     val = arr
@@ -361,7 +367,12 @@ function processHeader (request, key, val) {
   } else if (val === null) {
     val = ''
   } else {
+    // Coerce primitives (and reject unsafe coercions such as functions
+    // with a crafted toString/Symbol.toPrimitive).
     val = `${val}`
+    if (!isValidHeaderValue(val)) {
+      throw new InvalidArgumentError(`invalid ${key} header`)
+    }
   }
 
   if (headerName === 'host') {
 
@@ -10,6 +10,7 @@ const {
   RequestContentLengthMismatchError,
   ResponseContentLengthMismatchError,
   RequestAbortedError,
+  InvalidArgumentError,
   HeadersTimeoutError,
   HeadersOverflowError,
   SocketError,
@@ -993,8 +994,16 @@ function writeH1 (client, request) {
     }
     body = bodyStream.stream
     contentLength = bodyStream.length
-  } else if (util.isBlobLike(body) && request.contentType == null && body.type) {
-    headers.push('content-type', body.type)
+  } else if (util.isBlobLike(body) && request.contentType == null) {
+    const contentType = body.type
+    if (contentType) {
+      const contentTypeValue = `${contentType}`
+      if (!util.isValidHeaderValue(contentTypeValue)) {
+        util.errorRequest(client, request, new InvalidArgumentError('invalid content-type header'))
+        return false
+      }
+      headers.push('content-type', contentTypeValue)
+    }
   }
 
   if (body && typeof body.read === 'function') {
 
@@ -15,6 +15,28 @@ function calculateRetryAfterHeader (retryAfter) {
   return new Date(retryAfter).getTime() - current
 }
 
+function validatePartialResponseContentLength (headers, range, statusCode, retryCount) {
+  const contentLength = headers['content-length']
+  if (contentLength == null) {
+    return null
+  }
+
+  if (!Number.isFinite(range.start) || !Number.isFinite(range.end)) {
+    return null
+  }
+
+  const length = Number(contentLength)
+  const expectedLength = range.end - range.start + 1
+  if (!Number.isFinite(length) || length !== expectedLength) {
+    return new RequestRetryError('Content-Length mismatch', statusCode, {
+      headers,
+      data: { count: retryCount }
+    })
+  }
+
+  return null
+}
+
 class RetryHandler {
   constructor (opts, handlers) {
     const { retryOptions, ...dispatchOpts } = opts
@@ -229,6 +251,12 @@ class RetryHandler {
         return false
       }
 
+      const contentLengthError = validatePartialResponseContentLength(headers, contentRange, statusCode, this.retryCount)
+      if (contentLengthError != null) {
+        this.abort(contentLengthError)
+        return false
+      }
+
       const { start, size, end = size - 1 } = contentRange
 
       assert(this.start === start, 'content-range mismatch')
@@ -252,6 +280,12 @@ class RetryHandler {
           )
         }
 
+        const contentLengthError = validatePartialResponseContentLength(headers, range, statusCode, this.retryCount)
+        if (contentLengthError != null) {
+          this.abort(contentLengthError)
+          return false
+        }
+
         const { start, size, end = size - 1 } = range
         assert(
           start != null && Number.isFinite(start),
 
@@ -105,7 +105,7 @@ function validateCookiePath (path) {
 
     if (
       code < 0x20 || // exclude CTLs (0-31)
-      code === 0x7F || // DEL
+      code > 0x7E || // exclude DEL and non-ascii
       code === 0x3B // ;
     ) {
       throw new Error('Invalid cookie path')
@@ -114,16 +114,80 @@ function validateCookiePath (path) {
 }
 
 /**
- * I have no idea why these values aren't allowed to be honest,
- * but Deno tests these. - Khafra
+ * <let-dig> ::= <letter> | <digit>
+ *
+ * <letter> ::= any one of the 52 alphabetic characters A through Z in
+ * upper case and a through z in lower case
+ *
+ * <digit> ::= any one of the ten digits 0 through 9r
+ *
+ * @see https://www.rfc-editor.org/rfc/rfc1034#section-3.5
+ * @param {number} code
+ */
+function isLetterOrDigit (code) {
+  return (
+    (code >= 0x30 && code <= 0x39) || // 0-9
+    (code >= 0x41 && code <= 0x5A) || // A-Z
+    (code >= 0x61 && code <= 0x7A) // a-z
+  )
+}
+
+/**
+ * Validates a cookie domain against the "preferred name syntax".
+ *
+ * <domain>      ::= <subdomain> | " "
+ * <subdomain>   ::= <label> | <subdomain> "." <label>
+ * <label>       ::= <let-dig> [ [ <ldh-str> ] <let-dig> ]
+ * <ldh-str>     ::= <let-dig-hyp> | <let-dig-hyp> <ldh-str>
+ * <let-dig-hyp> ::= <let-dig> | "-"
+ *
+ * @see https://www.rfc-editor.org/rfc/rfc1034#section-3.5
+ * @see https://www.rfc-editor.org/rfc/rfc1123#section-2.1
+ * @see https://www.rfc-editor.org/rfc/rfc1035#section-2.3.4
  * @param {string} domain
  */
 function validateCookieDomain (domain) {
-  if (
-    domain.startsWith('-') ||
-    domain.endsWith('.') ||
-    domain.endsWith('-')
-  ) {
+  // <domain> ::= <subdomain> | " "
+  if (domain === ' ') {
+    return
+  }
+
+  if (domain.length > 255) {
+    throw new Error('Invalid cookie domain')
+  }
+
+  let labelLength = 0
+
+  for (let i = 0; i < domain.length; ++i) {
+    const code = domain.charCodeAt(i)
+
+    if (code === 0x2E) {
+      if (labelLength === 0) {
+        throw new Error('Invalid cookie domain')
+      }
+
+      if (domain.charCodeAt(i - 1) === 0x2D) { // "-"
+        throw new Error('Invalid cookie domain')
+      }
+
+      labelLength = 0
+      continue
+    }
+
+    if (labelLength === 0 && !isLetterOrDigit(code)) {
+      throw new Error('Invalid cookie domain')
+    }
+
+    if (!isLetterOrDigit(code) && code !== 0x2D) { // "-"
+      throw new Error('Invalid cookie domain')
+    }
+
+    if (++labelLength > 63) {
+      throw new Error('Invalid cookie domain')
+    }
+  }
+
+  if (labelLength === 0 || domain.charCodeAt(domain.length - 1) === 0x2D) { // "-"
     throw new Error('Invalid cookie domain')
   }
 }
@@ -266,7 +330,13 @@ function stringify (cookie) {
 
     const [key, ...value] = part.split('=')
 
-    out.push(`${key.trim()}=${value.join('=')}`)
+    const trimmedKey = key.trim()
+    const joinedValue = value.join('=')
+
+    validateCookieName(trimmedKey)
+    validateCookieValue(joinedValue)
+
+    out.push(`${trimmedKey}=${joinedValue}`)
   }
 
   return out.join('; ')
 
@@ -1,6 +1,6 @@
 {
   "name": "undici",
-  "version": "6.27.0",
+  "version": "6.28.0",
   "description": "An HTTP/1.1 client, written from scratch for Node.js",
   "homepage": "https://undici.nodejs.org",
   "bugs": {
 
@@ -13755,9 +13755,9 @@
       }
     },
     "node_modules/undici": {
-      "version": "6.27.0",
-      "resolved": "https://registry.npmjs.org/undici/-/undici-6.27.0.tgz",
-      "integrity": "sha512-YmfV3YnEDzXRC5lZ2jWtWWHKGUm1zIt8AhesR1tens+HTNv+YZlN/dp6G727LOvMJ8xjP9Be7Y2Sdr96LDm+pg==",
+      "version": "6.28.0",
+      "resolved": "https://registry.npmjs.org/undici/-/undici-6.28.0.tgz",
+      "integrity": "sha512-LIY910g9TI13YS95lrMFrs8Rm/u/irgHeTWoKCoteeJ04CUJ92eEfj0rVn+7VKMPBpUPiUoBKfhNyLI23EE/KA==",
       "inBundle": true,
       "license": "MIT",
       "engines": {
Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "undici",`
`3`		`- "version": "6.27.0",`
	`3`	`+ "version": "6.28.0",`
`4`	`4`	`"description": "An HTTP/1.1 client, written from scratch for Node.js",`
`5`	`5`	`"homepage": "https://undici.nodejs.org",`
`6`	`6`	`"bugs": {`