CVE-2026-36742Public exploit

Physical code execution via unauthenticated UART bootloader

Published May 13, 2026 · Updated May 13, 2026

Incorrect default permissions in Hiseeu C90 5.7.15 allow physically proximate attackers to execute code through the UART bootloader. Disconnecting the battery and applying external power activates a hidden debug mode whose UART console permits unrestricted memory access, firmware upload, and code execution without authentication. Exploitation requires opening the enclosure and attaching a 115200-baud UART adapter; successful access permits credential extraction, persistent firmware modification, or full device takeover.

CVSS severity6.8
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect default permissions in Hiseeu C90 5.7.15 allow physically proximate attackers to execute code through the UART bootloader. Disconnecting the battery and applying external power activates a hidden debug mode whose UART console permits unrestricted memory access, firmware upload, and code execution without authentication. Exploitation requires opening the enclosure and attaching a 115200-baud UART adapter; successful access permits credential extraction, persistent firmware modification, or full device takeover.

The record

CVE
CVE-2026-36742
Published
May 13, 2026
Updated
May 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-276, T1200, T1542.001
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2026CVE publishedPublication date reported by the CVE source.
  2. May 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.8CISA-ADPCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-276Incorrect Default Permissions
T1200Hardware Additions
T1542.001Pre-OS Boot: System Firmware

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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