A weakness has been identified in calcom cal.com and cal.diy up to 6.2.0. Impacted is the function createWebhookProcedure of the file packages/trpc/server/routers/viewer/webhook/util.ts of the component Webhook Handler. Executing a manipulation of the argument ID can lead to authorization bypass. It is possible to launch the attack remotely. The pull request to fix this issue awaits acceptance.
CVE-2026-109143 is a medium severity vulnerability in calcom cal.com and cal.diy up to version 6.2.0. It involves improper privilege management in the credentials.delete function of the Credentials Handler component, specifically in the /api/trpc/credentials/delete endpoint. The vulnerability arises from manipulation of the teamId argument, allowing remote attackers to potentially misuse privileges. The vendor has not responded to the disclosure, and no patch or fix information is currently available. Exploit details have been publicly disclosed but no known exploits are reported in the wild.
CVE-2026-104054 is a medium severity vulnerability in calcom cal.diy versions 6.0, 6.1, and 6.2.0. It involves missing authorization in the doesUserIdHaveAccessToBooking function within the PBAC Permission Engine component. The flaw can be exploited remotely without user interaction. Although exploit code is publicly available, no official fix has yet been accepted.
Cal.com Cal.diy versions 2.1.1 through 6.2.0 contain a stored cross-site scripting vulnerability in the BookingPageTagManager component that allows authenticated event owners to inject arbitrary JavaScript by supplying a malicious analytics tracking ID without sanitization. Attackers can close the inline script string literal with a crafted payload that executes in the browser of every visitor to the affected public booking page, enabling session cookie theft, forged authenticated requests, and wormable propagation by chaining with CSRF-able endpoints to persist payloads on additional events.
Cal.com (calcom/cal.diy) before 5.9.9 is vulnerable to unauthenticated remote code execution because it bundles a version of Next.js whose React Server Components (RSC) request handling deserializes attacker-controlled input. A remote attacker can send a crafted RSC request to the server and cause arbitrary code to be executed during server-side processing, without authentication or user interaction. The flaw derives from the upstream Next.js vulnerability CVE-2025-55182 and is resolved in 5.9.9 by updating the affected dependency.
Cal.com (calcom/cal.diy) versions through 4.7.15 contain a stored cross-site scripting vulnerability. The single booking view (e.g., https://app.cal.com/booking/<id>) renders booking-question field labels via React's dangerouslySetInnerHTML without sanitizing or escaping user input. An attacker who can create an event type with a malicious booking-question label can inject arbitrary HTML/JavaScript that executes when a victim opens the crafted booking URL. The issue is fixed in v4.7.16.
cal.com (calcom repository, later renamed cal.diy) is affected by a repository takeover vulnerability in its GitHub Actions workflows. The workflow pr.yml uses the pull_request_target trigger with the repository's default write permissions and passes them down to check-types.yml. check-types.yml then performs a 'dangerous' checkout of the attacker-submitted pull request code (via the dangerous-git-checkout action) and subsequently executes it (through yarn install and package.json scripts). An attacker can open a pull request whose code runs arbitrary commands with the repository's write-scoped GITHUB_TOKEN, allowing them to push commits, merge or mutate pull requests, add or delete comments, and delete or force-push branches, thereby compromising the repository. The main branch is affected; no patched version is available.
Cal.com (repository calcom/cal.diy) in versions <= 4.7.15 is vulnerable to cross-site scripting (XSS) on the publicly accessible single booking view (e.g., /booking/<id>). Booking question (form field) labels are rendered via React's dangerouslySetInnerHTML without proper input sanitization or CSP, so an attacker who can create an event type with a malicious booking question label can inject arbitrary HTML/JavaScript that executes when a victim visits the booking view URL. Self-hosted instances with open registration are particularly at risk. The issue is fixed in version 4.7.16.
Cal.com OSS ships lacks authorization on webhook teamId creation, allowing any authenticated user to create a webhook on any team via unvalidated teamId injection, then steal booking data, including fields like organizer/attendee emails and custom responses, and conditionally video-call passwords, by triggering webhook delivery.
cal.diy through 6.2.0 contains an open redirect vulnerability in the conferencing OAuth callback endpoint that allows attackers to redirect users to arbitrary URLs by crafting malicious state parameters. Attackers can exploit the unsigned state parameter and onErrorReturnTo field to silently redirect visitors from the trusted domain to attacker-controlled URLs for phishing attacks.
A vulnerability was determined in calcom cal.diy up to 4.9.4. Affected by this issue is the function getServerSideProps of the file apps/web/modules/bookings/views/bookings-single-view.getServerSideProps.tsx of the component Generic React API. This manipulation of the argument cancelledBy/rescheduledBy causes information disclosure. The attack can be initiated remotely. The exploit has been publicly disclosed and may be utilized. The vendor was contacted early about this disclosure but did not respond in any way.
A security flaw has been discovered in calcom cal.diy up to 4.9.4. The affected element is the function validateUrlForSSRF of the file apps/web/app/api/logo/route.ts of the component Logo API. The manipulation results in server-side request forgery. It is possible to launch the attack remotely. Attacks of this nature are highly complex. The exploitability is described as difficult. The exploit has been released to the public and may be used for attacks. The vendor was contacted early about this disclosure but did not respond in any way.
A vulnerability was identified in calcom cal.diy up to 4.9.4. Impacted is an unknown function. The manipulation leads to cross-site request forgery. It is possible to initiate the attack remotely. The exploit is publicly available and might be used. The vendor was contacted early about this disclosure but did not respond in any way.
CVE-2026-23478 is a critical vulnerability in cal.com versions from 3.1.6 up to before 6.0.7, where a flaw in a custom NextAuth JWT callback allows attackers to gain full authenticated access to any user's account by supplying a target email address via session.update(). This vulnerability arises from client-side enforcement of server-side security controls, violating proper authorization checks. It has a CVSS 4.0 score of 10.
Cal.com is open-source scheduling software. Prior to 5.9.8, A flaw in the login credentials provider allows an attacker to bypass password verification when a TOTP code is provided, potentially gaining unauthorized access to user accounts. This issue exists due to problematic conditional logic in the authentication flow. This vulnerability is fixed in 5.9.8.