CVE-2026-40003Public exploit

Code execution via unchecked USB write address

Published May 7, 2026 · Updated May 7, 2026

Out-of-bounds write in ZTE ZX297520V3 BootROM on the 7520V3 chip allows physically proximate attackers to execute code via USB. The USB download handler accepts a caller-supplied start address for command 0x7A without checking its target range, so repeated downloads can overwrite the saved return address on the BootROM stack. USB download mode must be triggered through a test point or failed flash loading, after which stack control bypasses Secure Boot image verification.

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

What happened

Out-of-bounds write in ZTE ZX297520V3 BootROM on the 7520V3 chip allows physically proximate attackers to execute code via USB. The USB download handler accepts a caller-supplied start address for command 0x7A without checking its target range, so repeated downloads can overwrite the saved return address on the BootROM stack. USB download mode must be triggered through a test point or failed flash loading, after which stack control bypasses Secure Boot image verification.

The record

CVE
CVE-2026-40003
Published
May 7, 2026
Updated
May 7, 2026
Vendor
ZTE Corporation
Product
ZX297520V3 BootROM
Classifications
CWE-787, T1200
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 7, 2026CVE publishedPublication date reported by the CVE source.
  2. May 7, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=7520V3 chip

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

ZTE Corporation · ZX297520V3 BootROMversion=7520V3 chip

Published CVSS scores

6.8NIST NVDCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
5.1ZTE CorporationCVSS:3.1/AV:P/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L

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-787Out-of-bounds Write
T1200Hardware Additions

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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