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Weekly Signal
Live intelligence Updated 19 Aug 2026 · 20:27 UTC

Realtek · AP-Router SDK, Rtl819x Jungle Software Development Kit

CVE-2021-35395

Realtek AP-Router SDK Buffer Overflow Vulnerability

Recommended action

Treat this as an immediate remediation priority. Apply updates per vendor instructions.

View response plan
CVSS9.8
EPSS98.0%
KEVYes
ExploitationConfirmed exploitation
PatchPatch or guidance available ↓

Assessment

Why it matters

CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 98.0%; technical severity is CVSS 9.8.

Realtek Jungle SDK version v2.x up to v3.4.14B provides an HTTP web server exposing a management interface that can be used to configure the access point. Two versions of this management interface exists: one based on Go-Ahead named webs and another based on Boa named boa. Both of them are affected by these vulnerabilities. Specifically, these binaries are vulnerable to the following issues: - stack buffer overflow in formRebootCheck due to unsafe copy of submit-url parameter - stack buffer overflow in formWsc due to unsafe copy of submit-url parameter - stack buffer overflow in formWlanMultipleAP due to unsafe copy of submit-url parameter - stack buffer overflow in formWlSiteSurvey due to unsafe copy of ifname parameter - stack buffer overflow in formStaticDHCP due to unsafe copy of hostname parameter - stack buffer overflow in formWsc due to unsafe copy of 'peerPin' parameter - arbitrary command execution in formSysCmd via the sysCmd parameter - arbitrary command injection in formWsc via the 'peerPin' parameter Exploitability of identified issues will differ based on what the end vendor/manufacturer did with the Realtek SDK webserver. Some vendors use it as-is, others add their own authentication implementation, some kept all the features from the server, some remove some of them, some inserted their own set of features. However, given that Realtek SDK implementation is full of insecure calls and that developers tends to re-use those examples in their custom code, any binary based on Realtek SDK webserver will probably contains its own set of issues on top of the Realtek ones (if kept). Successful exploitation of these issues allows remote attackers to gain arbitrary code execution on the device.

Who should care

  • Teams operating AP-Router SDK, Rtl819x Jungle Software Development Kit
  • Vulnerability and exposure management teams
  • Security operations teams monitoring exploitation activity

Response plan

What I would do

  1. Confirm whether AP-Router SDK, Rtl819x Jungle Software Development Kit is present in the environment.
  2. Identify affected versions and establish whether vulnerable services are exposed or reachable.
  3. Apply updates per vendor instructions.
  4. Review relevant security telemetry for evidence of attempted or successful exploitation.
  5. Document the remediation decision and track it to verified completion.

Vendor remediation

Patch and remediation links

Use the vendor source below to confirm the correct fixed version, package or mitigation for your affected product.

Technical details

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-20
Affected versions
Realtek AP-Router SDK; Realtek Rtl819x Jungle Software Development Kit (Start Including: 2.0, End Including: 3.4.14b)
Published
16 August 2021
Attack vector
Network
Privileges required
None
User interaction
None

Signal timeline

  1. CVE published
  2. Added to CISA KEV
  3. Latest EPSS score: 98.0%
  4. Signal calculated at 85

External references

Live public intelligence This assessment combines public-source evidence. Validate the affected product, version and exposure against your own environment before making a risk decision.