diff --git a/apps/backend/src/public-api/routes/v1/public.integrations.controller.ts b/apps/backend/src/public-api/routes/v1/public.integrations.controller.ts
index 0b6d8338..603ee01e 100644
--- a/apps/backend/src/public-api/routes/v1/public.integrations.controller.ts
+++ b/apps/backend/src/public-api/routes/v1/public.integrations.controller.ts
@@ -35,19 +35,9 @@ import { NotificationService } from '@gitroom/nestjs-libraries/database/prisma/n
 import { GetNotificationsDto } from '@gitroom/nestjs-libraries/dtos/notifications/get.notifications.dto';
 import { Readable } from 'stream';
 import { ssrfSafeDispatcher } from '@gitroom/nestjs-libraries/dtos/webhooks/ssrf.safe.dispatcher';
+import { VALID_POST_MEDIA_MIME_TYPES } from '@gitroom/helpers/utils/has.extension';
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const { fromBuffer } = require('file-type');
-
-const PUBLIC_API_ALLOWED_MIME = new Set<string>([
-  'image/jpeg',
-  'image/png',
-  'image/gif',
-  'image/webp',
-  'image/avif',
-  'image/bmp',
-  'image/tiff',
-  'video/mp4',
-]);
 import * as Sentry from '@sentry/nestjs';
 import {
   socialIntegrationList,
@@ -108,7 +98,7 @@ export class PublicIntegrationsController {
     }
     const buffer = Buffer.from(await response.arrayBuffer());
     const detected = await fromBuffer(buffer);
-    if (!detected || !PUBLIC_API_ALLOWED_MIME.has(detected.mime)) {
+    if (!detected || !VALID_POST_MEDIA_MIME_TYPES.has(detected.mime)) {
       throw new HttpException({ msg: 'Unsupported file type.' }, 400);
     }
     const mimetype = detected.mime;
diff --git a/libraries/helpers/src/utils/has.extension.ts b/libraries/helpers/src/utils/has.extension.ts
index 8f51a228..5716a0de 100644
--- a/libraries/helpers/src/utils/has.extension.ts
+++ b/libraries/helpers/src/utils/has.extension.ts
@@ -8,3 +8,26 @@ export const hasExtension = (
   const ext = extension.startsWith('.') ? extension : `.${extension}`;
   return path.toLowerCase().indexOf(ext.toLowerCase()) > -1;
 };
+
+const ALLOWED_POST_MEDIA: ReadonlyArray<{ ext: string; mime: string }> = [
+  { ext: 'png', mime: 'image/png' },
+  { ext: 'jpg', mime: 'image/jpeg' },
+  { ext: 'jpeg', mime: 'image/jpeg' },
+  { ext: 'gif', mime: 'image/gif' },
+  { ext: 'webp', mime: 'image/webp' },
+  { ext: 'mp4', mime: 'video/mp4' },
+];
+
+export const VALID_POST_MEDIA_EXTENSIONS = ALLOWED_POST_MEDIA.map(
+  (m) => m.ext
+);
+
+export const VALID_POST_MEDIA_MIME_TYPES = new Set<string>(
+  ALLOWED_POST_MEDIA.map((m) => m.mime)
+);
+
+export const isValidPostMediaUrl = (
+  path: string | undefined | null
+): boolean => {
+  return VALID_POST_MEDIA_EXTENSIONS.some((ext) => hasExtension(path, ext));
+};
diff --git a/libraries/helpers/src/utils/valid.url.path.ts b/libraries/helpers/src/utils/valid.url.path.ts
index aeedbe41..8e8e9a01 100644
--- a/libraries/helpers/src/utils/valid.url.path.ts
+++ b/libraries/helpers/src/utils/valid.url.path.ts
@@ -3,25 +3,20 @@ import {
   ValidatorConstraintInterface,
   ValidatorConstraint,
 } from 'class-validator';
+import { VALID_POST_MEDIA_EXTENSIONS } from './has.extension';
 
 @ValidatorConstraint({ name: 'checkValidExtension', async: false })
 export class ValidUrlExtension implements ValidatorConstraintInterface {
   validate(text: string, args: ValidationArguments) {
-    return (
-      !!text?.split?.('?')?.[0].endsWith('.png') ||
-      !!text?.split?.('?')?.[0].endsWith('.jpg') ||
-      !!text?.split?.('?')?.[0].endsWith('.jpeg') ||
-      !!text?.split?.('?')?.[0].endsWith('.gif') ||
-      !!text?.split?.('?')?.[0].endsWith('.webp') ||
-      !!text?.split?.('?')?.[0].endsWith('.mp4')
-    );
+    const path = text?.split?.('?')?.[0]?.toLowerCase?.();
+    if (!path) return false;
+    return VALID_POST_MEDIA_EXTENSIONS.some((ext) => path.endsWith('.' + ext));
   }
 
   defaultMessage(args: ValidationArguments) {
-    // here you can provide default error message if validation failed
-    return (
-      'File must have a valid extension: .png, .jpg, .jpeg, .gif, .webp, or .mp4'
-    );
+    return `File must have a valid extension: ${VALID_POST_MEDIA_EXTENSIONS.map(
+      (ext) => '.' + ext
+    ).join(', ')}`;
   }
 }
 
diff --git a/libraries/nestjs-libraries/src/chat/tools/integration.schedule.post.ts b/libraries/nestjs-libraries/src/chat/tools/integration.schedule.post.ts
index b2983de7..2f267659 100644
--- a/libraries/nestjs-libraries/src/chat/tools/integration.schedule.post.ts
+++ b/libraries/nestjs-libraries/src/chat/tools/integration.schedule.post.ts
@@ -12,6 +12,10 @@ import { Integration } from '@prisma/client';
 import { checkAuth } from '@gitroom/nestjs-libraries/chat/auth.context';
 import { stripHtmlValidation } from '@gitroom/helpers/utils/strip.html.validation';
 import { weightedLength } from '@gitroom/helpers/utils/count.length';
+import {
+  isValidPostMediaUrl,
+  VALID_POST_MEDIA_EXTENSIONS,
+} from '@gitroom/helpers/utils/has.extension';
 
 function countCharacters(text: string, type: string): number {
   if (type !== 'x') {
@@ -130,6 +134,19 @@ If the tools return errors, you would need to rerun it with the right parameters
         ).id;
         const finalOutput = [];
 
+        const invalidAttachment = inputData.socialPost
+          .flatMap((p) => p.postsAndComments)
+          .flatMap((p) => p.attachments ?? [])
+          .find((url: string) => !isValidPostMediaUrl(url));
+
+        if (invalidAttachment) {
+          return {
+            errors: `Attachment "${invalidAttachment}" is not supported. Valid extensions: ${VALID_POST_MEDIA_EXTENSIONS.map(
+              (ext) => '.' + ext
+            ).join(', ')}.`,
+          };
+        }
+
         const integrations = {} as Record<string, Integration>;
         for (const platform of inputData.socialPost) {
           integrations[platform.integrationId] =
diff --git a/libraries/nestjs-libraries/src/upload/custom.upload.validation.ts b/libraries/nestjs-libraries/src/upload/custom.upload.validation.ts
index c24c9504..87b99baa 100644
--- a/libraries/nestjs-libraries/src/upload/custom.upload.validation.ts
+++ b/libraries/nestjs-libraries/src/upload/custom.upload.validation.ts
@@ -3,19 +3,16 @@ import {
   Injectable,
   PipeTransform,
 } from '@nestjs/common';
+import {
+  VALID_POST_MEDIA_EXTENSIONS,
+  VALID_POST_MEDIA_MIME_TYPES,
+} from '@gitroom/helpers/utils/has.extension';
 // eslint-disable-next-line @typescript-eslint/no-var-requires
 const { fromBuffer } = require('file-type');
 
-const ALLOWED_MIME_TYPES = new Set<string>([
-  'image/jpeg',
-  'image/png',
-  'image/gif',
-  'image/webp',
-  'image/avif',
-  'image/bmp',
-  'image/tiff',
-  'video/mp4',
-]);
+const ALLOWED_EXTENSIONS_MESSAGE = `Valid extensions: ${VALID_POST_MEDIA_EXTENSIONS
+  .map((ext) => '.' + ext)
+  .join(', ')}`;
 
 @Injectable()
 export class CustomFileValidationPipe implements PipeTransform {
@@ -34,8 +31,10 @@ export class CustomFileValidationPipe implements PipeTransform {
     }
 
     const detected = await fromBuffer(value.buffer);
-    if (!detected || !ALLOWED_MIME_TYPES.has(detected.mime)) {
-      throw new BadRequestException('Unsupported file type.');
+    if (!detected || !VALID_POST_MEDIA_MIME_TYPES.has(detected.mime)) {
+      throw new BadRequestException(
+        `Unsupported file type. ${ALLOWED_EXTENSIONS_MESSAGE}`
+      );
     }
 
     const maxSize = this.getMaxSize(detected.mime);
@@ -61,7 +60,9 @@ export class CustomFileValidationPipe implements PipeTransform {
     } else if (mimeType.startsWith('video/')) {
       return 1024 * 1024 * 1024; // 1 GB
     } else {
-      throw new BadRequestException('Unsupported file type.');
+      throw new BadRequestException(
+        `Unsupported file type. ${ALLOWED_EXTENSIONS_MESSAGE}`
+      );
     }
   }
 }