# CVE-2026-104252: Vitess vttablet /twopcz reflected XSS

Source: https://junglewise.ai/threats/cve-2026-104252-vitess-vttablet-twopcz-reflected-xss  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-13. Updated: 2026-10-15  
License: CC BY 4.0 with a link back

CVE-2026-104252 · Severity: critical · CVSS 9.8 · Published 2026-10-13

Vitess vttablet is a database proxy that multiplexes HTTP debug endpoints on port 15999. An unauthenticated attacker can inject malicious JavaScript through URL parameters that are reflected unescaped in the HTML response, allowing same-origin access to sensitive debug endpoints that expose query logs, environment variables containing credentials, and internal statistics.

Technologies: [vitess.io/vitess (Go)](https://junglewise.ai/threats/technologies/vitess-io-vitess). Vendors: [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-104252 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-104252 being exploited in the wild.

**How severe is CVE-2026-104252?** Critical severity, with a CVSS score of 9.8, published 13 October 2026.

**Which products and versions are affected?** vitess.io/vitess (Go) < 0.23.5, SEMVER:introduced=0,fixed=0.23.5, SEMVER:introduced=0,fixed=0.23.5,introduced=0.24.0,fixed=0.24.2; Vitess v20.0.0 through v24.0.1 (all released versions).

**Is there a fix for CVE-2026-104252?** Yes. vitess.io/vitess (Go): upgrade to 0.23.5, 0.24.2 or later. Until then: Restrict the vttablet HTTP port (default 15999) to localhost-only access using network firewall rules or reverse proxy (nginx, envoy). Alternatively, configure a non-default ACL policy to deny unauthenticated access to debug endpoints, or use --tablet-allow-stats=false if debug endpoints are not needed for production traffic. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-104252 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-104252?** Check whether you run vitess.io/vitess (Go) or Vitess at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- vitess.io/vitess (Go): upgrade to 0.23.5, 0.24.2 or later

  ```sh
  go get vitess.io/vitess@v0.24.2
  ```


Restrict the vttablet HTTP port (default 15999) to localhost-only access using network firewall rules or reverse proxy (nginx, envoy). Alternatively, configure a non-default ACL policy to deny unauthenticated access to debug endpoints, or use --tablet-allow-stats=false if debug endpoints are not needed for production traffic.

## Technical details

The twopczHandler in twopcz.go reflects the Action and dtid form parameters directly into the HTML response via fmt.Fprintln() without HTML escaping, and serves the response as text/html with allow-all ACL policy. An attacker can craft a URL containing script tags or event handlers that execute in the operator's browser context, granting same-origin access to unauthenticated debug endpoints like /queryz, /querylogz, /txlogz, /debug/env, and /debug/vars. The bug has existed in all released versions since v20.0.0; the fix is only present in the main branch.

## Affected products

- Vitess Vitess v20.0.0 through v24.0.1 (all released versions)

## Identifiers

- CVE-2026-104252
- GHSA-v75v-6fpf-gvw8
- GO-2026-6798

## Timeline

- 2026-06-24: disclosed: Security report submitted to security@vitess.io
- 2026-06-09: patched: Fix committed to main branch (PR #20255, commit 3140c1846c) - not released
- 2026-10-15: advisory: GHSA-v75v-6fpf-gvw8 published

## Related threats

- [Vitess vttablet missing authorization in /debug/vrlog endpoint](https://junglewise.ai/threats/cve-2026-65959-vitess-vttablet-missing-authorization-in-debug-vrlog-endpoint)
- [GO-2026-4570 - Vitess users with backup storage access can write to arbitrary file paths in vitess.io/vitess](https://junglewise.ai/threats/cve-2026-27969-vitess-users-with-backup-storage-access-can-write-to-arbitrary)
- [GO-2026-4567 - Vitess users can gain unauthorized access to production deployment environments in vitess.io/vitess](https://junglewise.ai/threats/cve-2026-27965-vitess-users-with-backup-storage-access-can-gain-unauthorized)
- [GO-2024-3306 - Vitess allows HTML injection in /debug/querylogz and /debug/env in vitess.io/vitess](https://junglewise.ai/threats/cve-2024-53257-vitess-allows-html-injection-in-debug-querylogz-debug-env)
- [GO-2024-2826 - Denial of service attack by triggering unbounded memory usage in vitess.io/vitess](https://junglewise.ai/threats/cve-2024-32886-vitess-vulnerable-to-infinite-memory-consumption-and-vtgate-crash)