9.3

CVE-2026-57858: cal.com cal.com self-hosted (cal.diy) Cross-site Scripting

CVSS: 9.3v4.0CriticalDeferred
Published 12-08-2026Last modified 01-10-2026
Open JSON

Vulnerability summary

CVE-2026-57858 is a critical (CVSS 9.3) Cross-site Scripting vulnerability in cal.com cal.com self-hosted (cal.diy). EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 29.6% of scored vulnerabilities.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.3/10
010
Critical · v4.0 (CVE.org)
EPSS score
0.37%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 12-08-2026
    PublishedVulnerability first disclosed.
  2. 01-10-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

4 scores · 2 sources · 2 versions

EPSS trend

Probability

0.37%

Chance of exploitation in the next 30 days

Percentile

30%

Versus all other CVEs

30-day change

0.00 pp

From 0.37% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.37%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Cal.com1 product

1 vendor · 1 product

References

3 links