diff --git a/src/api/gramjs/apiBuilders/users.ts b/src/api/gramjs/apiBuilders/users.ts
index 3314f46b4..c2a6514c8 100644
--- a/src/api/gramjs/apiBuilders/users.ts
+++ b/src/api/gramjs/apiBuilders/users.ts
@@ -37,7 +37,7 @@ export function buildApiUserFullInfo(mtpUserFull: GramJs.users.UserFull): ApiUse
       birthday, personalChannelId, personalChannelMessage, sponsoredEnabled, stargiftsCount, botVerification,
       botCanManageEmojiStatus, settings, sendPaidMessagesStars, displayGiftsButton, disallowedGifts,
       starsRating, starsMyPendingRating, starsMyPendingRatingDate, mainTab, note,
-      noforwardsMyEnabled, noforwardsPeerEnabled,
+      noforwardsMyEnabled, noforwardsPeerEnabled, unofficialSecurityRisk,
     },
     users,
   } = mtpUserFull;
@@ -80,6 +80,7 @@ export function buildApiUserFullInfo(mtpUserFull: GramJs.users.UserFull): ApiUse
     note: note && buildApiFormattedText(note),
     noForwardsMyEnabled: noforwardsMyEnabled,
     noForwardsPeerEnabled: noforwardsPeerEnabled,
+    isUnofficialSecurityRisk: unofficialSecurityRisk,
   };
 }
 
diff --git a/src/api/types/users.ts b/src/api/types/users.ts
index 2d834f307..0f3a9fbe8 100644
--- a/src/api/types/users.ts
+++ b/src/api/types/users.ts
@@ -87,6 +87,7 @@ export interface ApiUserFullInfo {
   note?: ApiFormattedText;
   noForwardsMyEnabled?: boolean;
   noForwardsPeerEnabled?: boolean;
+  isUnofficialSecurityRisk?: boolean;
 }
 
 export type ApiUserType = 'userTypeBot' | 'userTypeRegular' | 'userTypeDeleted' | 'userTypeUnknown';
diff --git a/src/assets/localization/fallback.strings b/src/assets/localization/fallback.strings
index 0ccd11466..85eea8264 100644
--- a/src/assets/localization/fallback.strings
+++ b/src/assets/localization/fallback.strings
@@ -2814,3 +2814,4 @@
 "ReminderSetToast" = "You set up a reminder in **Saved Messages**";
 "NoForwardsRequestReject" = "Reject";
 "NoForwardsRequestAccept" = "Accept";
+"UnofficialSecurityRisk" = "{peer} uses an unofficial Telegram client — messages to this user may be less secure."
diff --git a/src/components/common/profile/ChatExtra.module.scss b/src/components/common/profile/ChatExtra.module.scss
index 01e7ef501..f5ead89df 100644
--- a/src/components/common/profile/ChatExtra.module.scss
+++ b/src/components/common/profile/ChatExtra.module.scss
@@ -144,6 +144,18 @@
   cursor: var(--custom-cursor, pointer);
 }
 
+.unofficialSecurityRisk {
+  margin-bottom: 0.5rem;
+  padding-inline: 0.5rem;
+  line-height: 1.25;
+  text-wrap: balance;
+}
+
+.riskIcon {
+  margin-inline-end: 0.25rem;
+  color: var(--color-error);
+}
+
 @include mixins.on-active-vt('profileNote') {
   &::view-transition-image-pair(.noteText) {
     overflow: hidden;
diff --git a/src/components/common/profile/ChatExtra.tsx b/src/components/common/profile/ChatExtra.tsx
index af5d69afe..481cd71f7 100644
--- a/src/components/common/profile/ChatExtra.tsx
+++ b/src/components/common/profile/ChatExtra.tsx
@@ -26,6 +26,7 @@ import {
   isUserRightBanned,
 } from '../../../global/helpers';
 import { getIsChatMuted } from '../../../global/helpers/notifications';
+import { getPeerTitle } from '../../../global/helpers/peers';
 import {
   selectBotAppPermissions,
   selectChat,
@@ -392,6 +393,12 @@ const ChatExtra = ({
 
   return (
     <div className={buildClassName('ChatExtra', className)} style={createVtnStyle('chatExtra')}>
+      {user && userFullInfo?.isUnofficialSecurityRisk && (
+        <div className={styles.unofficialSecurityRisk}>
+          <Icon className={buildClassName(styles.riskIcon, 'in-text-icon')} name="info-filled" />
+          {lang('UnofficialSecurityRisk', { peer: getPeerTitle(lang, user) })}
+        </div>
+      )}
       {personalChannel && (
         <div className={styles.personalChannel} style={createVtnStyle('personalChannel')}>
           <h3 className={styles.personalChannelTitle}>{oldLang('ProfileChannel')}</h3>
diff --git a/src/types/language.d.ts b/src/types/language.d.ts
index d70f98a56..24568a2a9 100644
--- a/src/types/language.d.ts
+++ b/src/types/language.d.ts
@@ -3625,6 +3625,9 @@ export interface LangPairWithVariables<V = LangVariable> {
   'RankEditText': {
     'user': V;
   };
+  'UnofficialSecurityRisk': {
+    'peer': V;
+  };
 }
 
 export interface LangPairPlural {