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PatchSiren cyber security CVE debrief

CVE-2021-35395 Realtek CVE debrief

CVE-2021-35395 is a Realtek AP-Router SDK buffer overflow that CISA added to its Known Exploited Vulnerabilities catalog on 2021-11-03. Because it is listed in KEV, defenders should treat it as an active-risk issue and move quickly to vendor-provided remediation for any products that embed the SDK.

Vendor
Realtek
Product
AP-Router SDK
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2021-11-03
Original CVE updated
2021-11-03
Advisory published
2021-11-03
Advisory updated
2021-11-03

Who should care

Organizations that use or ship products built on Realtek AP-Router SDK, especially router and embedded networking vendors, should care most. Security and asset-management teams should also prioritize it because CISA has flagged it as known exploited.

Technical summary

The available official record identifies the issue as a buffer overflow in Realtek AP-Router SDK. The corpus provided here does not include a vendor advisory, CVSS vector, or detailed impact statement, so only the confirmed vulnerability class and product scope are stated. The key defensive signal is its inclusion in CISA KEV, which indicates known exploitation.

Defensive priority

Very high. CISA listed this CVE in KEV with a remediation due date of 2021-11-17, so affected environments should be treated as urgent patch candidates.

Recommended defensive actions

  • Identify any products, firmware, or appliances that include Realtek AP-Router SDK.
  • Apply vendor updates or mitigation guidance as soon as possible.
  • If patching is not immediately available, isolate exposed devices and restrict access to management and internet-facing interfaces.
  • Verify remediation across all embedded and downstream products that may bundle the SDK.
  • Track this CVE in vulnerability management and exception workflows until closure.

Evidence notes

Supported facts in this debrief come from the supplied CISA KEV source item and the official CVE/NVD/CISA resource links. The source corpus confirms the CVE ID, vendor project, product name, vulnerability class, KEV status, dateAdded 2021-11-03, and dueDate 2021-11-17. No additional impact or exploitation details were assumed beyond those supplied.

Sources and references

Verified primary and authoritative sources

  • CVE-2021-35395 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2021-35395

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2021-35395 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2021-35395

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

    cisa_kev

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.