---
id: "CVE-2026-129427"
page: "https://infrastack.ai/live/CVE-2026-129427"
kind: "vulnerability"
aliases: ["CVE-2026-129427"]
title: "Cervantes: avatar upload XSS plus auth bypass takes over accounts"
severity: "high"
cvss: 8.7
epss: null
exploited: false
status: "open"
category: "other"
products: [{"name": "cervantes", "fixed": [], "affected": "v1.3-beta", "ecosystem": "vendor"}]
ecosystems: []
tags: ["auth-bypass", "cervantes", "other", "self-hosted", "xss"]
not_affected_if: []
published_at: "2026-11-14T12:17:44+00:00"
first_seen_at: "2026-11-14T12:28:31+00:00"
updated_at: "2026-11-14T12:31:38+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-129427", "first_seen_at": "2026-11-14T12:28:31+00:00"}, {"source": "analyst", "url": "https://www.rapid7.com/db/vulnerabilities/cve-2026-129427/", "first_seen_at": "2026-11-14T12:31:38+00:00", "cites": ["https://www.rapid7.com/db/vulnerabilities/cve-2026-129427/", "https://github.com/CervantesSec/cervantes/releases"]}]
exploit_sources: []
---

# Cervantes: avatar upload XSS plus auth bypass takes over accounts

Link for people: https://infrastack.ai/live/CVE-2026-129427 (this .md is for agents)

Cervantes v1.3-beta has a stored cross-site scripting flaw in avatar uploads, chained with an authentication bypass in the /Attachments path. An attacker can run script in another user's browser with that user's elevated privileges, leading to account takeover.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:cervantes affected v1.3-beta fixed no fixed version listed

## How to check

Check the deployed Cervantes version (v1.3-beta is the only version named as affected). Also check earlier versions if you run them: not confirmed either way. Check whether untrusted users can reach the instance and upload avatars.

## Fix

Unknown for this CVE. The vendor's v1.4.0-beta release notes describe hardening of avatar uploads (images only), attachment serving and CSP, but do not name this CVE. Upgrading to v1.4.0-beta or later is a reasonable step; not confirmed as the fix.

## Timeline

- 2026-11-14T12:28:31+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-129427
- 2026-11-14T12:31:38+00:00 analyst https://www.rapid7.com/db/vulnerabilities/cve-2026-129427/ — NVD/Rapid7: CervantesSec cervantes v1.3-beta, CVSS PR:L suggests an account is needed, though the description says auth bypass in /Attachments (unclear). No vendor advisory or CVE-specific fix found. v1.4.0-beta release notes (23 Oct) describe avatar images-only, attachments served by app endpoint with sandbox, SVG/XHTML refused, enforced CSP; plausibly the fix but not stated for this CVE.

## Documents

- [describes] Rapid7 DB: CVE-2026-129427 https://www.rapid7.com/db/vulnerabilities/cve-2026-129427/
- [mentions] CervantesSec/cervantes releases (v1.3-beta, v1.4.0-beta) https://github.com/CervantesSec/cervantes/releases

## From the sources

Stored XSS via avatar upload chained with an authentication bypass in /Attachments leads to ATO
in Cervantes version v1.3-beta could allow an attacker to execute arbitrary code in another user's browser with elevated privileges

---

_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_