Security readout for executives and security teams
Plain-English summary
CVE-2021-21740 is an information leak in ZTE's ZXHN H2640 residential gateway firmware V10.0.0C6_TY. A person able to insert a prepared USB disk could cause the media service to expose unauthorized directory information. The source bundle does not provide CVSS, patch details, or exploitation evidence.
Executive priority
Prioritize this for affected ZTE gateway fleets with accessible USB ports or enabled media sharing. Business urgency is lower than remote-code-execution issues, but exposed gateway information can still aid follow-on intrusion or privacy-impacting investigation.
Technical view
The vulnerability affects the digital media player/DMS component of ZTE ZXHN H2640 V10.0.0C6_TY. The described issue involves symbolic-link handling on an inserted USB disk, allowing unauthorized directory information disclosure. Available sources do not identify a CWE, attack complexity, privilege requirements, or fixed firmware version.
Likely exposure
Exposure appears limited to organizations or homes using ZTE ZXHN H2640 gateways on firmware V10.0.0C6_TY, especially where USB media features are enabled or physically accessible. The source bundle does not list other models or firmware versions.
Exploitation context
The cited description requires inserting a USB disk with a symbolic link into the gateway. No source in the bundle reports public exploitation, weaponized tooling, or CISA KEV inclusion. Treat exploitation status as unconfirmed.
Researcher notes
The record is sparse: no CVSS vector, CWE, fixed version, or detailed vendor remediation is included. Analysis should stay scoped to ZXHN H2640 V10.0.0C6_TY and the DMS symbolic-link information disclosure described by the CVE sources.
Mitigation direction
- Inventory ZTE ZXHN H2640 gateways and confirm firmware versions.
- Check ZTE support guidance for corrected firmware or official mitigations.
- Restrict physical access to gateway USB ports.
- Disable DMS or USB media sharing if supported by the device configuration.
- Replace or isolate affected devices if no vendor-supported fix is available.
Validation and detection
- Confirm whether any ZXHN H2640 devices run V10.0.0C6_TY.
- Review whether USB media or DMS functionality is enabled.
- Verify physical controls around deployed residential gateways.
- Check ZTE advisory channels for firmware remediation status.
- Document any compensating controls where firmware cannot be updated.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CVE-2021-21740 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://support.zte.com.cn/support/news/LoopholeInfoDetail.aspx?newsId=1017244CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.