calcom cal.com up to 6.0.6 JWT Call session.update client-side enforcement of server-side security

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
8.4$0-$5k0.00

Summaryinfo

A vulnerability classified as critical has been found in calcom cal.com up to 6.0.6. This vulnerability affects the function session.update of the component JWT Call Handler. Performing a manipulation results in client-side enforcement of server-side security. This vulnerability is known as CVE-2026-23478. Remote exploitation of the attack is possible. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in calcom cal.com up to 6.0.6. It has been classified as critical. This affects the function session.update of the component JWT Call Handler. The manipulation with an unknown input leads to a client-side enforcement of server-side security vulnerability. CWE is classifying the issue as CWE-602. The product is composed of a server that relies on the client to implement a mechanism that is intended to protect the server. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Cal.com is open-source scheduling software. From 3.1.6 to before 6.0.7, there is a vulnerability in a custom NextAuth JWT callback that allows attackers to gain full authenticated access to any user's account by supplying a target email address via session.update(). This vulnerability is fixed in 6.0.7.

The advisory is shared at github.com. This vulnerability is uniquely identified as CVE-2026-23478 since 01/13/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details are known, but no exploit is available.

Upgrading to version 6.0.7 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-2413). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Vendor

Name

Version

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 8.5
VulDB Meta Temp Score: 8.4

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Client-side enforcement of server-side security
CWE: CWE-602
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: cal.com 6.0.7

Timelineinfo

01/13/2026 CVE reserved
01/14/2026 +1 days Advisory disclosed
01/14/2026 +0 days VulDB entry created
02/04/2026 +21 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-7hg4-x4pr-3hrg
Status: Confirmed

CVE: CVE-2026-23478 (🔒)
GCVE (CVE): GCVE-0-2026-23478
GCVE (VulDB): GCVE-100-341025
EUVD: 🔒

Entryinfo

Created: 01/14/2026 08:52
Updated: 02/04/2026 03:14
Changes: 01/14/2026 08:52 (68), 01/14/2026 12:45 (1), 02/04/2026 03:14 (18)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Might our Artificial Intelligence support you?

Check our Alexa App!