# CVE-2026-57858: Cal.com Cal.diy 6.2.0 Stored XSS via BookingPageTagManager Analytics Tracking ID

> Authenticated users can inject JavaScript into booking pages via analytics IDs, stealing visitor sessions and enabling wormable propagation.

- **Severity:** Critical 9.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 12 Aug 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-5m2w-xrqj-9hhh

## What is CVE-2026-57858?

CVE-2026-57858 is a critical cross-site scripting vulnerability in Cal.com Self-Hosted (Cal.diy), published on 12 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-57858?


## How do I fix CVE-2026-57858?

No fix has been published for CVE-2026-57858 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-57858 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-57858 exists.

Public exploit code:

- Wormable exploit for CVE-2026-57858 (github_poc): https://github.com/zylideum/CVE-2026-57858

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-57858 and fix it if it is affected.

What it is: CVE-2026-57858 is a critical cross-site scripting vulnerability in Cal.com Self-Hosted (Cal.diy), published on 12 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-57858 exists.

Affected product: Cal.com Self-Hosted (Cal.diy). No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-57858/ (Markdown: https://insights.sbomify.com/CVE-2026-57858/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-57858
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-57858
- OSV: https://osv.dev/vulnerability/CVE-2026-57858

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-57858/
Summaries are generated and may contain mistakes; the official description above is the record.