CVE-2021-21739
A ZTE's product of the transport network access layer has a security vulnerability. Because the...
A ZTE's product of the transport network access layer has a security vulnerability. Because the system does not sufficiently verify the data reliability, attackers could replace an authenticated optical module on the equipment with an unauthenticated one, bypassing system authentication and detection, thus affecting signal transmission. This affects: <ZXCTN 6120H><V5.10.00B24>
Attack profile
How easy it is to exploit
- Attack vector
- Physical
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- None
Exploit likelihood
What each source reports
NVD Score used
A ZTE's product of the transport network access layer has a security vulnerability. Because the system does not sufficiently verify the data reliability, attackers could replace an authenticated optical module on the equipment with an unauthenticated one, bypassing system authentication and detection, thus affecting signal transmission. This affects: <ZXCTN 6120H><V5.10.00B24>
- Record
CVE-2021-21739- CVSS 3.1
- 4.6 Medium
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N - CVSS 2.0
- 2.1 Low
AV:L/AC:L/Au:N/C:N/I:P/A:N - Weakness
- CWE-345
- Updated
- 2026-11-02
CVE List No score
A ZTE's product of the transport network access layer has a security vulnerability. Because the system does not sufficiently verify the data reliability, attackers could replace an authenticated optical module on the equipment with an unauthenticated one, bypassing system authentication and detection, thus affecting signal transmission. This affects: <ZXCTN 6120H><V5.10.00B24>
- Record
CVE-2021-21739- Updated
- 2026-11-02
EUVDEUVD-2021-8911 No score
A ZTE's product of the transport network access layer has a security vulnerability. Because the system does not sufficiently verify the data reliability, attackers could replace an authenticated optical module on the equipment with an unauthenticated one, bypassing system authentication and detection, thus affecting signal transmission. This affects: <ZXCTN 6120H><V5.10.00B24>
- Record
EUVD-2021-8911- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-2r85-x553-vqw2 No score
A ZTE's product of the transport network access layer has a security vulnerability. Because the...
A ZTE's product of the transport network access layer has a security vulnerability. Because the system does not sufficiently verify the data reliability, attackers could replace an authenticated optical module on the equipment with an unauthenticated one, bypassing system authentication and detection, thus affecting signal transmission. This affects: <ZXCTN 6120H><V5.10.00B24>
- Record
GHSA-2r85-x553-vqw2- Weakness
- CWE-345
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | ||
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-21739 is a medium vulnerability (CVSS 4.6) in Zte Zxctn 6120h Firmware, published August 5, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.25%, the 16th percentile. No source names a fixed version.