Buffer overflow in ZTE Zx297520v3

CVE-2026-40003

ZTE ZX297520V3 BootROM contains a vulnerability that allows arbitrary memory writes via USB. Attackers can exploit the lack of target address validation in the USB download mode to write data to any location in BootROM runtime memory, thereby overwriting the stack, hijacking the execution flow, bypassing the Secure Boot signature verification mechanism, and achieving unauthorized code execution.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.1 (Medium). Vector: CVSS:3.1/AV:P/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:L.

EPSS exploit prediction

EPSS: 0.003 (15.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 15.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-40003: held from 0.003 to 0.003.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: -0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2026-40003?
CVE-2026-40003 is a medium-severity vulnerability in ZTE Zx297520v3, classified under Out-of-bounds Write. CVSS score: 5.1/10. Published 2026-05-07.
How severe is CVE-2026-40003?
Medium severity. CVSS v3 base score is 5.1 out of 10.
Is CVE-2026-40003 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.