diff --git a/src/components/NcRichText/autolink.ts b/src/components/NcRichText/autolink.ts
index 5b3911d57a..3cb1ef02af 100644
--- a/src/components/NcRichText/autolink.ts
+++ b/src/components/NcRichText/autolink.ts
@@ -123,11 +123,26 @@ export const getRoute = (router: Router, url: string): string | null => {
 
 	const isAbsoluteURL = /^https?:\/\//.test(url)
 
+	// URL is a "mailto:", "tel:" or any custom app protocol link
+	const isNonHttpLink = /^[a-z][a-z0-9+.-]*:.+/.test(url)
+	if (!isAbsoluteURL && isNonHttpLink) {
+		return null
+	}
+
 	// URL is not a link to this Nextcloud server instance => not an app route
 	if (isAbsoluteURL && !url.startsWith(getBaseUrl())) {
 		return null
 	}
 
+	if (!isAbsoluteURL && !url.startsWith('/')) {
+		// Relative URL without a leading slash are not allowed
+		// VueRouter handles such urls according to the URL RFC,
+		// for example, being on /call/abc page, link "def" is resolved as "/call/def" relative to "/call/".
+		// We don't want to support such links,
+		// so relative URL MUST start with a slash.
+		return null
+	}
+
 	// URL relative to the instance root
 	const relativeUrl = isAbsoluteURL ? removePrefixes(url, getBaseUrl(), '/index.php') : url
 
diff --git a/tests/unit/components/NcRichText/autoLink.spec.js b/tests/unit/components/NcRichText/autoLink.spec.js
index ea1d1adcb8..5843f58d0b 100644
--- a/tests/unit/components/NcRichText/autoLink.spec.js
+++ b/tests/unit/components/NcRichText/autoLink.spec.js
@@ -10,6 +10,8 @@ import { getBaseUrl, getRootUrl } from '@nextcloud/router'
 
 vi.mock('@nextcloud/router')
 
+Vue.use(VueRouter)
+
 describe('autoLink', () => {
 	describe('getRoute', () => {
 		describe.each([
@@ -108,7 +110,7 @@ describe('autoLink', () => {
 			})
 		})
 
-		it('should not get route from relative link with base /nextcloud/index.php/apps/test/foo', () => {
+		it('should not get route from relative link with base in the link /nextcloud/index.php/apps/test/foo', () => {
 			getBaseUrl.mockReturnValue('https://cloud.ltd/nextcloud')
 			getRootUrl.mockReturnValue('/nextcloud')
 			const router = createRouter({
@@ -122,6 +124,49 @@ describe('autoLink', () => {
 			expect(getRoute(router, '/nextcloud/index.php/apps/test/foo')).toBe(null)
 		})
 
+		it('should not get route from relative link without a leading slash', async () => {
+			getBaseUrl.mockReturnValue('https://cloud.ltd/')
+			getRootUrl.mockReturnValue('')
+			const routerTalk = new VueRouter({
+				mode: 'abstract',
+				base: '',
+				routes: [
+					{ path: '/apps/spreed', name: 'root', component: {} },
+					{ path: '/call/:id', name: 'call', component: {} },
+				],
+			})
+			routerTalk.push('/call/12345678')
+
+			expect(getRoute(routerTalk, 'abcdefgh')).toBe(null)
+			expect(getRoute(routerTalk, 'call/abcdefgh')).toBe(null)
+		})
+
+		describe('Non-HTTP links', () => {
+			const routerTalk = new VueRouter({
+				mode: 'abstract',
+				base: '',
+				routes: [
+					{ path: '/apps/spreed', name: 'root' },
+					{ path: '/call/:id', name: 'call' },
+				],
+			})
+			getBaseUrl.mockReturnValue('https://cloud.ltd/')
+			getRootUrl.mockReturnValue('')
+			routerTalk.push('/call/12345678')
+
+			it('should not handle mailto: link as a relative link', () => {
+				expect(getRoute(routerTalk, 'mailto:email@nextcloud.ltd')).toBe(null)
+			})
+
+			it('should not handle nc: link as a relative link', () => {
+				expect(getRoute(routerTalk, 'nc://login')).toBe(null)
+			})
+
+			it('should not handle a1.b-c+d: link as a relative link', () => {
+				expect(getRoute(routerTalk, 'a1.b-c+d://action')).toBe(null)
+			})
+		})
+
 		// getRoute doesn't have to guarantee Talk Desktop compatibility, but checking just in case
 		describe('with Talk Desktop router - no router base and invalid getRootUrl', () => {
 			it.each([