What is the CVSS score of CVE-2021-27708?

CVE-2021-27708 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: 7.6%.

Is there a public PoC exploit available for CVE-2021-27708?

Yes, a public proof-of-concept exploit is available for CVE-2021-27708. Prioritise patching immediately. EPSS: 7.6%.

X5000r Firmware CVE-2021-27708

CRITICAL

OS Command Injection (CWE-78)

2021-04-14 cve@mitre.org

Command Injection X5000r Firmware A720R Firmware TOTOLINK

9.8

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-78 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization OS command sanitization, avoid shell exec MITRE ATT&CK 2 techniques across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available.
Exploit ScenarioDerived	A remote attacker could execute arbitrary operating system commands on the host by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.

No patch listed yet 7.6% exploitation probability (EPSS)

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AnalysisAI

Command Injection in TOTOLINK X5000R router with firmware v9.1.0u.6118_B20201102, and TOTOLINK A720R router with firmware v4.1.5cu.470_B20200911 allows remote attackers to execute arbitrary OS. 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.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Avoid passing user input to shell commands. Use language-specific APIs instead of shell execution. Apply strict input validation with allowlists.

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as OS Command Injection (CWE-78), which allows attackers to execute arbitrary operating system commands on the host. Command Injection in TOTOLINK X5000R router with firmware v9.1.0u.6118_B20201102, and TOTOLINK A720R router with firmware v4.1.5cu.470_B20200911 allows remote attackers to execute arbitrary OS commands by sending a modified HTTP request. This occurs because the function executes glibc's system function with untrusted input. In the function, "command" parameter is directly passed to the attacker, allowing them to control the "command" field to attack the OS. Affected products include: Totolink X5000R Firmware, Totolink A720R Firmware.

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Exploit and PoC references, threat intelligence from 22 sources

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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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionNVD

Command Injection in TOTOLINK X5000R router with firmware v9.1.0u.6118_B20201102, and TOTOLINK A720R router with firmware v4.1.5cu.470_B20200911 allows remote attackers to execute arbitrary OS commands by sending a modified HTTP request. This occurs because the function executes glibc's system function with untrusted input. In the function, "command" parameter is directly passed to the attacker, allowing them to control the "command" field to attack the OS.

Threat Intelligence Overview

EPSS Score

7.6%

Top 6% exploitable

Exploit

POC

Public exploit code exists

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC Yes

EPSS 7.6%

Patch available No

Active threat No

Deciding rule

CRITICAL severity + public POC available

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +8

CVSS: +49

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

OS Command Injection CRITICAL

OS command injection occurs when an application passes unsanitized user input directly into system shell commands.

Affected Products (CPE)NVD

cpe:2.3:o:totolink:x5000r_firmware:9.1.0u.6118_b20201102:*:*:*:*:*:*:*

cpe:2.3:o:totolink:a720r_firmware:4.1.5cu.470_b20200911:*:*:*:*:*:*:*

More in X5000r Firmware

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CVE-2023-30013 CRITICAL Emergency POC

9.8 May 05

TOTOLINK X5000R V9.1.0u.6118_B20201102 and V9.1.0u.6369_B20230113 contain a command insertion vulnerability in setting/s

CVE-2025-13184 CRITICAL Emergency POC

9.8 Dec 10

Unauthenticated remote attackers can enable Telnet on TOTOLINK X5000R AX1800 routers running firmware V9.1.0u.6369_B2023

CVE-2023-31569 CRITICAL Act Now POC

9.8 Jun 06

TOTOLINK X5000R V9.1.0cu.2350_B20230313 was discovered to contain a command injection via the setWanCfg function. Rated

CVE-2025-70327 CRITICAL Act Now POC

9.8 Feb 23

Argument injection in TOTOLINK X5000R router v9.1.0cu via setDiagnosisCfg handler allows unauthenticated remote code exe

CVE-2024-32353 CRITICAL Act Now POC

9.8 May 14

TOTOLINK X5000R V9.1.0cu.2350_B20230313 was discovered to contain a command injection vulnerability via the 'port' param

CVE-2024-28639 CRITICAL Act Now POC

9.8 Mar 16

Buffer Overflow vulnerability in TOTOLink X5000R V9.1.0u.6118-B20201102 and A7000R V9.1.0u.6115-B20201022, allow remote

CVE-2023-6612 CRITICAL Act Now POC

9.8 Dec 08

A vulnerability was found in Totolink X5000R 9.1.0cu.2300_B20230112. Rated critical severity (CVSS 9.8), this vulnerabil

CVE-2023-45984 CRITICAL Act Now POC

9.8 Oct 16

TOTOLINK X5000R V9.1.0u.6118_B20201102 and TOTOLINK A7000R V9.1.0u.6115_B20201022 was discovered to contain a stack over

CVE-2023-36950 CRITICAL Act Now POC

9.8 Oct 16

TOTOLINK X5000R V9.1.0u.6118_B20201102 and TOTOLINK A7000R V9.1.0u.6115_B20201022 was discovered to contain a stack over

CVE-2023-36947 CRITICAL Act Now POC

9.8 Oct 16

TOTOLINK X5000R V9.1.0u.6118_B20201102 and TOTOLINK A7000R V9.1.0u.6115_B20201022 was discovered to contain a stack over

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TOTOLINK X5000R B20210419 was discovered to contain a remote code execution (RCE) vulnerability via the setTracerouteCfg

CVE-2023-39617 CRITICAL Act Now POC

9.8 Aug 21

TOTOLINK X5000R_V9.1.0cu.2089_B20211224 and X5000R_V9.1.0cu.2350_B20230313 were discovered to contain a remote code exec

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