CVE-2021-35394

Exploitation

Exploited in the wild. Listed in the CISA Known Exploited Vulnerabilities catalog on 2021-12-10. Federal remediation due 2021-12-24.

SSVC decision

• ExploitationactiveCISA reports credible evidence of active exploitation.
• AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
• Technical ImpacttotalSuccessful exploitation gives total control of the vulnerable component.

CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.

EPSS probability

99.86% probability of exploitation activity in the next 30 days.

EPSS percentile

Ranks above 100.0% of scored records. A rank, not a probability.

NVD base score

9.8 (CVSS v3.x), scored by the NVD independently of the CNA.

NVD CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NVD analysis status

Analyzed. NVD last modified this record on 2026-06-17.

Red Hat severity

No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

Published

2021-08-16 11:07Z5 YR AGO

Last updated

2025-10-21 23:25Z10 MO AGO

Reserved

2021-06-23

Assigning CNA

mitre

Record state

PUBLISHED

Severity

Critical (CVSS 9.8)

CNA CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses

• CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')Base

Data version

5.1

Document digest

a0fb968a09210bc131f3e88018de714bccf22feb5adb52863585f1633a24de1c

• www.securityfocus.comhttps://www.securityfocus.com/archive/1/534765x_refsource_MISC
• www.realtek.comhttps://www.realtek.com/en/cu-1-en/cu-1-taiwan-enx_refsource_MISC
• www.realtek.comhttps://www.realtek.com/images/safe-report/Realtek_APRouter_SDK_Advisory-CVE-2021-35392_35395.pdfx_refsource_MISC
• www.iot-inspector.comhttps://www.iot-inspector.com/blog/advisory-multiple-issues-realtek-sdk-iot-supply-chainx_refsource_MISC
• www.cisa.govhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35394government-resource