CVE-2026-23478
CVE-2026-23478 is a critical-severity vulnerability in Cal Cal.com with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-602.
Key facts
- Severity: Critical (CVSS 3.x base score 9.8)
- CVSS v4: 10.0
- EPSS exploit prediction: 0% (32nd percentile)
- Actively exploited: Not listed in CISA KEV
- EU (EUVD) id: EUVD-2026-2413
- Weakness: CWE-602
- Affected product: Cal Cal.com
- Published:
- Last modified:
Description
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.
Frequently asked questions
- What is CVE-2026-23478?
- 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.
- How severe is CVE-2026-23478?
- CVE-2026-23478 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
- Is CVE-2026-23478 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2026-23478?
- CVE-2026-23478 affects Cal Cal.com. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2026-23478?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
- Does CVE-2026-23478 have an EU (EUVD) identifier?
- Yes. CVE-2026-23478 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-2413.
- When was CVE-2026-23478 published?
- CVE-2026-23478 was published on 2026-01-13 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:a:cal:cal.com:*:*:*:*:*:*:*:*
More vulnerabilities in Cal Cal.com
- CVE-2025-66489 — Critical (CVSS 9.8): Cal.com is open-source scheduling software. Prior to 5.9.8, A flaw in the login credentials provider allows an attacker…
- CVE-2023-1647 — High (CVSS 8.8): Improper Access Control in GitHub repository calcom/cal.com prior to 2.7.
- CVE-2023-37919 — Medium (CVSS 6.5): Cal.com is open-source scheduling software. A vulnerability allows active sessions associated with an account to remain…
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