---
title: "CVE-2026-104252: Vitess vttablet /twopcz reflected XSS"
url: https://erroneo.us/security/cve/CVE-2026-104252/
description: "CVE-2026-104252 (vitess.io/vitess (Go)): Vitess is a database clustering system for horizontal scaling of MySQL. Prior to 23.0.5 and 24.0.2, twopczHandler…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-10-13
date_modified: 2026-10-15
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-104252"
kev: false
cvss: 9.8
epss: 0.00885
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.9% , percentile 59: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 59% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes vitess.io/vitess (Go) < 0.23.5, fixed in 0.23.5 ; vitess.io/vitess (Go) >= 0.24.0, < 0.24.2, fixed in 0.24.2 . Check your lockfile, including transitive dependencies.

## What it is

Vitess is a database clustering system for horizontal scaling of MySQL. Prior to 23.0.5 and 24.0.2, twopczHandler in go/vt/vttablet/tabletserver/twopcz.go writes the Action and dtid form values from the vttablet and vtcombo /twopcz HTTP debug endpoint into a text/html response without HTML escaping. Under the default allow-all ACL policy, a remote unauthenticated attacker can send an operator a crafted request that executes script in the operator's browser after the request is opened. The script runs with the vttablet debug origin and can read same-origin diagnostic endpoints that expose query, transaction, environment, variable, or profiling data available in that deployment. This issue is fixed in versions 23.0.5 and 24.0.2.

## Affected packages

- Go `vitess.io/vitess` < 0.23.5 → fixed: 0.23.5
- Go `vitess.io/vitess` >= 0.24.0, < 0.24.2 → fixed: 0.24.2

## Affected products (CVE record)

- vitessio vitess: < 23.0.5, >= 24.0.0, < 24.0.2

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.89% probability of exploitation activity in the next 30 days; percentile 59.

## Sources

- [GitHub Advisory GHSA-v75v-6fpf-gvw8](https://github.com/advisories/GHSA-v75v-6fpf-gvw8)
- [CVE.org record CVE-2026-104252](https://www.cve.org/CVERecord?id=CVE-2026-104252)
- [NVD entry CVE-2026-104252](https://nvd.nist.gov/vuln/detail/CVE-2026-104252)
- [github.com](https://github.com/vitessio/vitess/security/advisories/GHSA-v75v-6fpf-gvw8)
- [github.com](https://github.com/vitessio/vitess/pull/20255)
- [github.com](https://github.com/vitessio/vitess/pull/20273)
- [github.com](https://github.com/vitessio/vitess/pull/20274)
- [github.com](https://github.com/vitessio/vitess/commit/3140c1846cd120db34f33b2083139b4ab638aed2)
- [github.com](https://github.com/vitessio/vitess/commit/976e1e0d78f9d29d02e5e31b4aa7e180648f08af)
- [github.com](https://github.com/vitessio/vitess/commit/c1ed96302e658190168c971afdac730cf70e43f7)
- [github.com](https://github.com/vitessio/vitess/releases/tag/v23.0.5)
- [github.com](https://github.com/vitessio/vitess/releases/tag/v24.0.2)

---
Source page: https://erroneo.us/security/cve/CVE-2026-104252/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt