How severe is CVE-2021-27708?

CVE-2021-27708 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-27708 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-27708?

CVE-2021-27708 primarily affects Totolink X5000r Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-27708?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-27708 published?

CVE-2021-27708 was published on 2021-04-14 and last updated on 2026-06-17.

CVE-2021-27708

CVE-2021-27708 is a critical-severity vulnerability in Totolink X5000r Firmware with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 10.0
EPSS exploit prediction: 8% (94th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-78
Affected product: Totolink X5000r Firmware
Published: 2021-04-14
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2021-27708?: 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.
How severe is CVE-2021-27708?: CVE-2021-27708 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-27708 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 8% (94th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-27708?: CVE-2021-27708 primarily affects Totolink X5000r Firmware. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-27708?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-27708 published?: CVE-2021-27708 was published on 2021-04-14 and last updated on 2026-06-17.

References

Affected products (2)

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 vulnerabilities in Totolink X5000r Firmware

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CVE-2024-32353 — Critical (CVSS 9.8): TOTOLINK X5000R V9.1.0cu.2350_B20230313 was discovered to contain a command injection vulnerability via the 'port'…
CVE-2024-28639 — Critical (CVSS 9.8): Buffer Overflow vulnerability in TOTOLink X5000R V9.1.0u.6118-B20201102 and A7000R V9.1.0u.6115-B20201022, allow remote…
CVE-2023-45984 — Critical (CVSS 9.8): TOTOLINK X5000R V9.1.0u.6118_B20201102 and TOTOLINK A7000R V9.1.0u.6115_B20201022 was discovered to contain a stack…
CVE-2023-36950 — Critical (CVSS 9.8): TOTOLINK X5000R V9.1.0u.6118_B20201102 and TOTOLINK A7000R V9.1.0u.6115_B20201022 was discovered to contain a stack…

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