Security readout for executives and security teams
Plain-English summary
This flaw could let someone on the same network as a vulnerable NETGEAR R7800 router run code on the device without logging in. Because router compromise can expose traffic, change network settings, or support persistence, treat affected devices as high priority.
Executive priority
Prioritize remediation for any R7800 used in business networks or shared Wi-Fi environments. The business risk is router takeover without authentication from an adjacent network position, but current sources do not prove active exploitation.
Technical view
CVE-2021-34947 is an unauthenticated, network-adjacent out-of-bounds write in NETGEAR R7800 net-cgi parsing of the soap_block_table file. The CVE states improper validation can write past an allocated structure and execute code as root. Affected version evidence names R7800 firmware 1.0.2.82.
Likely exposure
Exposure is most likely where NETGEAR R7800 routers, especially firmware 1.0.2.82, are reachable from untrusted LAN, Wi-Fi, or guest network segments.
Exploitation context
The source bundle supports unauthenticated, low-complexity, network-adjacent remote code execution. It does not show CISA KEV listing or provide evidence of active exploitation in the wild.
Researcher notes
Track this as CWE-787 and ZDI-CAN-13055. The key technical condition is improper validation during soap_block_table parsing in net-cgi, leading to root-context code execution. Source evidence is specific to R7800 version 1.0.2.82.
Mitigation direction
- Check the NETGEAR advisory for affected models and vendor-approved fixed firmware.
- Update affected R7800 devices according to NETGEAR guidance.
- Restrict router management and device services to trusted network segments.
- Separate guest or untrusted Wi-Fi from router administrative paths.
- Replace unsupported devices if vendor guidance cannot confirm remediation.
Validation and detection
- Inventory NETGEAR R7800 routers and record firmware versions.
- Confirm whether firmware 1.0.2.82 is present.
- Review network segmentation for untrusted adjacent access to router services.
- Verify remediation status against the NETGEAR PSV-2021-0129 advisory.
- Document exceptions where firmware cannot be verified or 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.
CWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-34947 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
- High
- CVSS
- 8.8 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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 vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.8HighVector: CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- ZDI-21-1116CVE reference · x_research-advisory
- vendor-provided URLCVE reference · vendor-advisory
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.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.