What is the CVSS score of CVE-2021-31756?

CVE-2021-31756 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 2.9%.

Is there a public PoC exploit available for CVE-2021-31756?

Yes, a public proof-of-concept exploit is available for CVE-2021-31756. Prioritise patching immediately. EPSS: 2.9%.

Ac11 Firmware CVE-2021-31756

CRITICAL

Out-of-bounds Write (CWE-787)

2021-05-07 cve@mitre.org

Buffer Overflow RCE Memory Corruption Tenda Ac11 Firmware

9.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.8 CRITICAL

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

CVE Published

May 07, 2021 - 23:15 nvd

CRITICAL 9.8

DescriptionNVD

An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /gofrom/setwanType allows attackers to execute arbitrary code on the system via a crafted post request. This occurs when input vector controlled by malicious attack get copied to the stack variable.

AnalysisAI

An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

Technical ContextAI

This vulnerability is classified as Out-of-bounds Write (CWE-787), which allows attackers to write data beyond allocated buffer boundaries leading to code execution or crashes. An issue was discovered on Tenda AC11 devices with firmware through 02.03.01.104_CN. A stack buffer overflow vulnerability in /gofrom/setwanType allows attackers to execute arbitrary code on the system via a crafted post request. This occurs when input vector controlled by malicious attack get copied to the stack variable. Affected products include: Tenda Ac11 Firmware. Version information: through 02.03.01.104.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Validate write boundaries, use memory-safe languages, enable compiler protections (ASLR, stack canaries).