diff --git a/.changeset/funny-icons-develop.md b/.changeset/funny-icons-develop.md
new file mode 100644
index 000000000000..eacb88108a0f
--- /dev/null
+++ b/.changeset/funny-icons-develop.md
@@ -0,0 +1,5 @@
+---
+'@rocket.chat/meteor': patch
+---
+
+Security Hotfix (https://docs.rocket.chat/docs/security-fixes-and-updates)
diff --git a/apps/meteor/app/otr/server/methods/updateOTRAck.ts b/apps/meteor/app/otr/server/methods/updateOTRAck.ts
index eaba2906ed06..445f0c4de87a 100644
--- a/apps/meteor/app/otr/server/methods/updateOTRAck.ts
+++ b/apps/meteor/app/otr/server/methods/updateOTRAck.ts
@@ -1,6 +1,9 @@
 import type { ServerMethods } from '@rocket.chat/ui-contexts';
+import { Rooms } from '@rocket.chat/models';
+import { check } from 'meteor/check';
 import { Meteor } from 'meteor/meteor';
 
+import { canAccessRoomAsync } from '../../../authorization/server';
 import notifications from '../../../notifications/server/lib/Notifications';
 
 declare module '@rocket.chat/ui-contexts' {
@@ -11,10 +14,45 @@ declare module '@rocket.chat/ui-contexts' {
 }
 
 Meteor.methods<ServerMethods>({
-	updateOTRAck({ message, ack }) {
-		if (!Meteor.userId()) {
+	async updateOTRAck({ message, ack }) {
+		const uid = Meteor.userId();
+
+		if (!uid) {
 			throw new Meteor.Error('error-invalid-user', 'Invalid user', { method: 'updateOTRAck' });
 		}
+
+		check(ack, String);
+		check(message, {
+			_id: String,
+			rid: String,
+			msg: String,
+			t: String,
+			ts: Date,
+			u: {
+				_id: String,
+				username: String,
+				name: String,
+			},
+			_updatedAt: Date,
+			urls: Array,
+			mentions: Array,
+			channels: Array,
+		});
+
+		if (message?.t !== 'otr') {
+			throw new Meteor.Error('error-invalid-message', 'Invalid message type', { method: 'updateOTRAck' });
+		}
+
+		const room = await Rooms.findOneById(message.rid, { projection: { t: 1, _id: 1, uids: 1 } });
+
+		if (!room) {
+			throw new Meteor.Error('error-invalid-room', 'Invalid room', { method: 'updateOTRAck' });
+		}
+
+		if (!(await canAccessRoomAsync(room, { _id: uid })) || (room.uids && (!message.u._id || !room.uids.includes(message.u._id)))) {
+			throw new Meteor.Error('error-invalid-user', 'Invalid user, not in room', { method: 'updateOTRAck' });
+		}
+
 		const otrStreamer = notifications.streamRoomMessage;
 		otrStreamer.emit(message.rid, { ...message, otr: { ack } });
 	},
diff --git a/apps/meteor/client/views/marketplace/AppDetailsPage/tabs/AppDetails/AppDetails.tsx b/apps/meteor/client/views/marketplace/AppDetailsPage/tabs/AppDetails/AppDetails.tsx
index 04fdad70ed5c..d334944423f8 100644
--- a/apps/meteor/client/views/marketplace/AppDetailsPage/tabs/AppDetails/AppDetails.tsx
+++ b/apps/meteor/client/views/marketplace/AppDetailsPage/tabs/AppDetails/AppDetails.tsx
@@ -2,11 +2,13 @@ import { Box, ButtonGroup, Callout, Chip, Margins } from '@rocket.chat/fuselage'
 import { ExternalLink } from '@rocket.chat/ui-client';
 import type { TranslationKey } from '@rocket.chat/ui-contexts';
 import { useTranslation } from '@rocket.chat/ui-contexts';
+import DOMPurify from 'dompurify';
 import type { ReactElement } from 'react';
 import React from 'react';
 
 import ScreenshotCarouselAnchor from '../../../components/ScreenshotCarouselAnchor';
 import type { AppInfo } from '../../../definitions/AppInfo';
+import { purifyOptions } from '../../../lib/purifyOptions';
 import AppDetailsAPIs from './AppDetailsAPIs';
 
 const AppDetails = ({ app }: { app: AppInfo }): ReactElement => {
@@ -50,7 +52,14 @@ const AppDetails = ({ app }: { app: AppInfo }): ReactElement => {
 						<Box fontScale='h4' mbe='x8' color='titles-labels'>
 							{t('Description')}
 						</Box>
-						<Box dangerouslySetInnerHTML={{ __html: isMarkdown ? detailedDescription.rendered : description }} withRichContent />
+						<Box
+							dangerouslySetInnerHTML={{
+								__html: isMarkdown
+									? DOMPurify.sanitize(detailedDescription.rendered, purifyOptions)
+									: DOMPurify.sanitize(description, purifyOptions),
+							}}
+							withRichContent
+						/>
 					</Box>
 
 					<Box is='section'>
diff --git a/apps/meteor/client/views/marketplace/AppDetailsPage/tabs/AppReleases/AppReleasesItem.tsx b/apps/meteor/client/views/marketplace/AppDetailsPage/tabs/AppReleases/AppReleasesItem.tsx
index a8bf56d957b3..d6cd88300494 100644
--- a/apps/meteor/client/views/marketplace/AppDetailsPage/tabs/AppReleases/AppReleasesItem.tsx
+++ b/apps/meteor/client/views/marketplace/AppDetailsPage/tabs/AppReleases/AppReleasesItem.tsx
@@ -1,9 +1,11 @@
 import { Accordion, Box } from '@rocket.chat/fuselage';
 import { useTranslation } from '@rocket.chat/ui-contexts';
+import DOMPurify from 'dompurify';
 import type { ReactElement } from 'react';
 import React from 'react';
 
 import { useTimeAgo } from '../../../../../hooks/useTimeAgo';
+import { purifyOptions } from '../../../lib/purifyOptions';
 
 type IRelease = {
 	version: string;
@@ -36,7 +38,7 @@ const AppReleasesItem = ({ release, ...props }: ReleaseItemProps): ReactElement
 	return (
 		<Accordion.Item title={title} {...props}>
 			{release.detailedChangelog?.rendered ? (
-				<Box dangerouslySetInnerHTML={{ __html: release.detailedChangelog?.rendered }} color='default' />
+				<Box dangerouslySetInnerHTML={{ __html: DOMPurify.sanitize(release.detailedChangelog?.rendered, purifyOptions) }} color='default' />
 			) : (
 				<Box color='default'>{t('No_release_information_provided')}</Box>
 			)}
diff --git a/apps/meteor/client/views/marketplace/lib/purifyOptions.ts b/apps/meteor/client/views/marketplace/lib/purifyOptions.ts
new file mode 100644
index 000000000000..cef1a2c8c707
--- /dev/null
+++ b/apps/meteor/client/views/marketplace/lib/purifyOptions.ts
@@ -0,0 +1,50 @@
+export const purifyOptions = {
+	ALLOWED_TAGS: [
+		'b',
+		'i',
+		'em',
+		'strong',
+		'br',
+		'p',
+		'ul',
+		'ol',
+		'li',
+		'article',
+		'aside',
+		'figure',
+		'section',
+		'summary',
+		'h1',
+		'h2',
+		'h3',
+		'h4',
+		'h5',
+		'h6',
+		'hgroup',
+		'div',
+		'hr',
+		'span',
+		'wbr',
+		'abbr',
+		'acronym',
+		'cite',
+		'code',
+		'dfn',
+		'figcaption',
+		'mark',
+		's',
+		'samp',
+		'sub',
+		'sup',
+		'var',
+		'time',
+		'q',
+		'del',
+		'ins',
+		'rp',
+		'rt',
+		'ruby',
+		'bdi',
+		'bdo',
+	],
+};
diff --git a/packages/gazzodown/package.json b/packages/gazzodown/package.json
index 8ecdb2b006a0..2865b2339bf1 100644
--- a/packages/gazzodown/package.json
+++ b/packages/gazzodown/package.json
@@ -74,6 +74,8 @@
 		"react": "*"
 	},
 	"dependencies": {
+		"@types/dompurify": "^3.0.5",
+		"dompurify": "^3.1.7",
 		"highlight.js": "^11.5.1",
 		"react-error-boundary": "^3.1.4"
 	},
diff --git a/packages/gazzodown/src/emoji/EmojiRenderer.tsx b/packages/gazzodown/src/emoji/EmojiRenderer.tsx
index 7a4ca5324930..7d8d6dbfe1bf 100644
--- a/packages/gazzodown/src/emoji/EmojiRenderer.tsx
+++ b/packages/gazzodown/src/emoji/EmojiRenderer.tsx
@@ -1,5 +1,6 @@
 import { MessageEmoji, ThreadMessageEmoji } from '@rocket.chat/fuselage';
 import type * as MessageParser from '@rocket.chat/message-parser';
+import DOMPurify from 'dompurify';
 import { ReactElement, useMemo, useContext, memo } from 'react';
 
 import { MarkupInteractionContext } from '../MarkupInteractionContext';
@@ -13,11 +14,12 @@ const EmojiRenderer = ({ big = false, preview = false, ...emoji }: EmojiProps):
 	const { detectEmoji } = useContext(MarkupInteractionContext);
 
 	const fallback = useMemo(() => ('unicode' in emoji ? emoji.unicode : `:${emoji.shortCode ?? emoji.value.value}:`), [emoji]);
+	const sanitizedFallback = DOMPurify.sanitize(fallback);
 
 	const descriptors = useMemo(() => {
-		const detected = detectEmoji?.(fallback);
+		const detected = detectEmoji?.(sanitizedFallback);
 		return detected?.length !== 0 ? detected : undefined;
-	}, [detectEmoji, fallback]);
+	}, [detectEmoji, sanitizedFallback]);
 
 	return (
 		<>
@@ -34,8 +36,8 @@ const EmojiRenderer = ({ big = false, preview = false, ...emoji }: EmojiProps):
 					)}
 				</span>
 			)) ?? (
-				<span role='img' aria-label={fallback.charAt(0) === ':' ? fallback : undefined}>
-					{fallback}
+				<span role='img' aria-label={sanitizedFallback.charAt(0) === ':' ? sanitizedFallback : undefined}>
+					{sanitizedFallback}
 				</span>
 			)}
 		</>