diff --git a/.circleci/config.yml b/.circleci/config.yml
index 4379e6e..b8fe8cf 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -67,7 +67,7 @@ workflows:
           branches:
             only:
             - develop
-            - PM-4482
+            - PM-4975
             
     # Production builds are exectuted only on tagged commits to the
     # master branch.
diff --git a/src/common/helper.js b/src/common/helper.js
index 90cf857..f343a80 100644
--- a/src/common/helper.js
+++ b/src/common/helper.js
@@ -630,7 +630,20 @@ function convertBigIntDeep (value) {
   }
   return value
 }
-
+/**
+ * Validate that a member handle contains only permitted characters.
+ * Handles with special chars like <, >, ?, spaces, or raw Unicode
+ * that were created via legacy systems should return a clean 404.
+ * @param {String} handle the member handle
+ * @throws {NotFoundError} if handle contains invalid characters
+ */
+function validateHandle (handle) {
+  // Topcoder handles: 2–50 chars, letters, digits, hyphens, underscores, periods only
+  const VALID_HANDLE_RE = /^[a-zA-Z0-9\-_.]{2,50}$/
+  if (!VALID_HANDLE_RE.test(handle)) {
+    throw new errors.NotFoundError(`Member with handle: "${handle}" doesn't exist`)
+  }
+}
 module.exports = {
   wrapExpress,
   autoWrapExpress,
@@ -661,5 +674,6 @@ module.exports = {
   secureMemberAddressData,
   truncateLastName,
   bigIntToNumber,
-  convertBigIntDeep
+  convertBigIntDeep,
+  validateHandle
 }
diff --git a/src/controllers/MemberController.js b/src/controllers/MemberController.js
index a772468..a18e67c 100644
--- a/src/controllers/MemberController.js
+++ b/src/controllers/MemberController.js
@@ -9,6 +9,7 @@ const service = require('../services/MemberService')
  * @param {Object} res the response
  */
 async function getMember (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.getMember(req.authUser, req.params.handle, req.query)
   res.send(result)
 }
@@ -18,6 +19,7 @@ async function getMember (req, res) {
  * @param {Object} res the response
  */
 async function getProfileCompleteness (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.getProfileCompleteness(req.authUser, req.params.handle, req.query)
   res.send(result)
 }
@@ -38,6 +40,7 @@ async function getMemberUserIdSignature (req, res) {
  * @param {Object} res the response
  */
 async function getMemberSkill (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.getMemberSkill(req.authUser, req.params.handle, req.params.skillid)
   res.send(result)
 }
@@ -48,6 +51,7 @@ async function getMemberSkill (req, res) {
  * @param {Object} res the response
  */
 async function updateMember (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.updateMember(req.authUser, req.params.handle, req.query, req.body)
   res.send(result)
 }
@@ -58,6 +62,7 @@ async function updateMember (req, res) {
  * @param {Object} res the response
  */
 async function updateHandle (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.updateHandle(req.authUser, req.params.handle, req.query, req.body)
   res.send(result)
 }
@@ -68,6 +73,7 @@ async function updateHandle (req, res) {
  * @param {Object} res the response
  */
 async function verifyEmail (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.verifyEmail(req.authUser, req.params.handle, req.query)
   res.send(result)
 }
@@ -78,6 +84,7 @@ async function verifyEmail (req, res) {
  * @param {Object} res the response
  */
 async function uploadPhoto (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.uploadPhoto(req.authUser, req.params.handle, req.files)
   res.send(result)
 }
@@ -88,6 +95,7 @@ async function uploadPhoto (req, res) {
  * @param {Object} res the response
  */
 async function deleteMember (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.deleteMember(req.authUser, req.params.handle, req.body)
   res.send(result)
 }
@@ -98,6 +106,7 @@ async function deleteMember (req, res) {
  * @param {Object} res the response
  */
 async function confirmProfileData (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.confirmProfileData(req.authUser, req.params.handle)
   res.send(result)
 }
@@ -108,6 +117,7 @@ async function confirmProfileData (req, res) {
  * @param {Object} res the response
  */
 async function downloadProfile (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const pdfStream = await service.downloadProfile(req.authUser, req.params.handle)
   res.setHeader('Content-Type', 'application/pdf')
   res.setHeader('Content-Disposition', `attachment; filename="topcoder-profile-${req.params.handle}.pdf"`)
@@ -120,6 +130,7 @@ async function downloadProfile (req, res) {
  * @param {Object} res the response
  */
 async function getMemberSendgridEmails (req, res) {
+  const handle = decodeURIComponent(req.params.handle)
   const result = await service.getMemberSendgridEmails(req.authUser, req.params.handle)
   res.send(result)
 }
diff --git a/src/services/MemberService.js b/src/services/MemberService.js
index 83910b8..3aa9621 100644
--- a/src/services/MemberService.js
+++ b/src/services/MemberService.js
@@ -101,7 +101,7 @@ function omitMemberAttributes (currentUser, mb) {
   const hasSensitiveDataRole = helper.hasSensitiveDataRole(currentUser)
   const isM2M = currentUser && currentUser.isMachine
   const isSelf = currentUser && currentUser.handle && mb.handleLower &&
-    currentUser.handle.trim().toLowerCase() === mb.handleLower.trim().toLowerCase()
+    currentUser.handle.toLowerCase() === mb.handleLower.toLowerCase()
   const canSeeIdentityVerified = isM2M || hasSensitiveDataRole || isSelf
   const canSeeRecentActivity = isM2M || hasSensitiveDataRole || isSelf
   const canSeeFullAddress = canManageMember || hasSensitiveDataRole
@@ -202,6 +202,7 @@ function getCountryNameFromCode (isoCode3) {
  * @returns {Object} the member profile data
  */
 async function getMemberData (handle, query, allowedFields = MEMBER_FIELDS) {
+  helper.validateHandle(handle)
   // validate and parse query parameter
   const selectFields = helper.parseCommaSeparatedString(query.fields, allowedFields) || allowedFields
 
@@ -251,7 +252,7 @@ async function getMember (currentUser, handle, query) {
   const hasSensitiveDataRole = helper.hasSensitiveDataRole(currentUser)
   const isM2M = currentUser && currentUser.isMachine
   const isSelf = currentUser && currentUser.handle &&
-    currentUser.handle.trim().toLowerCase() === handle.trim().toLowerCase()
+    currentUser.handle.toLowerCase() === handle.toLowerCase()
 
   const canSeePhones = isM2M || hasSensitiveDataRole || isSelf
   const canSeeRecentActivity = isM2M || hasSensitiveDataRole || isSelf
@@ -345,7 +346,7 @@ getMember.schema = {
   handle: Joi.string().required(),
   query: Joi.object().keys({
     fields: Joi.string()
-  })
+  }).unknown(true)
 }
 
 /**
@@ -369,6 +370,7 @@ function buildSendgridEmailActivityQuery (email, startTime, endTime) {
  * @returns {Array} up to the most recent SendGrid message activity records
  */
 async function getMemberSendgridEmails (currentUser, handle) {
+  helper.validateHandle(handle)
   if (!currentUser || (!currentUser.isMachine && !helper.hasAdminRole(currentUser))) {
     throw new errors.ForbiddenError('You are not allowed to view SendGrid email activity.')
   }
@@ -586,7 +588,7 @@ getProfileCompleteness.schema = {
   query: Joi.object().keys({
     fields: Joi.string(),
     toast: Joi.string()
-  })
+  }).unknown(true)
 }
 
 /**
@@ -610,7 +612,7 @@ getMemberUserIdSignature.schema = {
   currentUser: Joi.any(),
   query: Joi.object().keys({
     type: Joi.string().valid('userflow').required()
-  }).required()
+  }).unknown(true).required()
 }
 
 /**
@@ -622,6 +624,7 @@ getMemberUserIdSignature.schema = {
  * @returns {Object} the updated member data
  */
 async function updateMember (currentUser, handle, query, data) {
+  helper.validateHandle(handle)
   const operatorId = currentUser.userId || currentUser.sub
   const member = await helper.getMemberByHandle(handle)
   // check authorization
@@ -778,7 +781,7 @@ updateMember.schema = {
   handle: Joi.string().required(),
   query: Joi.object().keys({
     fields: Joi.string()
-  }),
+  }).unknown(true),
   data: Joi.object().keys({
     handle: Joi.forbidden(),
     handleLower: Joi.forbidden(),
@@ -820,6 +823,7 @@ updateMember.schema = {
  * @returns {Object} the updated member data
  */
 async function updateHandle (currentUser, handle, query, data) {
+  helper.validateHandle(handle)
   const operatorId = currentUser.userId || currentUser.sub
   const member = await helper.getMemberByHandle(handle)
 
@@ -925,7 +929,7 @@ updateHandle.schema = {
   handle: Joi.string().required(),
   query: Joi.object().keys({
     fields: Joi.string()
-  }),
+  }).unknown(true),
   data: Joi.object().keys({
     newHandle: Joi.string().required()
   }).required()
@@ -988,7 +992,7 @@ verifyEmail.schema = {
   handle: Joi.string().required(),
   query: Joi.object().keys({
     token: Joi.string().required()
-  }).required()
+  }).unknown(true).required()
 }
 
 /**
@@ -1070,6 +1074,7 @@ async function uploadPhoto (currentUser, handle, files) {
  * @returns {Object} the deletion result
  */
 async function deleteMember (currentUser, handle, data) {
+  helper.validateHandle(handle)
   if (!currentUser || (!currentUser.isMachine && !helper.hasAdminRole(currentUser))) {
     throw new errors.ForbiddenError('You are not allowed to delete the member.')
   }
@@ -1939,6 +1944,7 @@ async function aggregatePDFData (currentUser, handle) {
  * @returns {Stream} PDF stream
  */
 async function downloadProfile (currentUser, handle) {
+  helper.validateHandle(handle)
   // Validate handle exists
   const member = await helper.getMemberByHandle(handle)
 
diff --git a/src/services/MemberTraitService.js b/src/services/MemberTraitService.js
index bfaa0f2..1b99f96 100644
--- a/src/services/MemberTraitService.js
+++ b/src/services/MemberTraitService.js
@@ -206,7 +206,7 @@ async function getTraits (currentUser, handle, query) {
   const hasSensitiveDataRole = helper.hasSensitiveDataRole(currentUser)
   const isM2M = currentUser && currentUser.isMachine
   const isSelf = currentUser && currentUser.handle &&
-    currentUser.handle.trim().toLowerCase() === handle.trim().toLowerCase()
+    currentUser.handle.toLowerCase() === handle.toLowerCase()
 
   // can read private personalisation info on a member
   const canReadPrivate = isM2M || hasSensitiveDataRole || isSelf
@@ -284,7 +284,7 @@ getTraits.schema = {
   query: Joi.object().keys({
     traitIds: Joi.string(),
     fields: Joi.string()
-  })
+  }).unknown(true)
 }
 
 /**
@@ -659,7 +659,7 @@ removeTraits.schema = {
   handle: Joi.string().required(),
   query: Joi.object().keys({
     traitIds: Joi.string() // if not provided, then all member traits are removed
-  })
+  }).unknown(true)
 }
 /**
 * This function is used to calculate a deduction to the skill score used in the talent search