How severe is CVE-2020-26728?

CVE-2020-26728 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-2020-26728 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-26728?

CVE-2020-26728 primarily affects Tenda Ac9 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-2020-26728?

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-2020-26728 published?

CVE-2020-26728 was published on 2022-02-11 and last updated on 2026-06-17.

CVE-2020-26728

CVE-2020-26728 is a critical-severity vulnerability in Tenda Ac9 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.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 4% (89th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Tenda Ac9 Firmware
Published: 2022-02-11
Last modified: 2026-06-17

Description

A vulnerability was discovered in Tenda AC9 v3.0 V15.03.06.42_multi and Tenda AC9 V1.0 V15.03.05.19(6318)_CN which allows for remote code execution via shell metacharacters in the guestuser field to the __fastcall function with a POST request.

Frequently asked questions

What is CVE-2020-26728?: A vulnerability was discovered in Tenda AC9 v3.0 V15.03.06.42_multi and Tenda AC9 V1.0 V15.03.05.19(6318)_CN which allows for remote code execution via shell metacharacters in the guestuser field to the __fastcall function with a POST request.
How severe is CVE-2020-26728?: CVE-2020-26728 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-2020-26728 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-26728?: CVE-2020-26728 primarily affects Tenda Ac9 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-2020-26728?: 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-2020-26728 published?: CVE-2020-26728 was published on 2022-02-11 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:o:tenda:ac9_firmware:15.03.06.42_multi:*:*:*:*:*:*:*
cpe:2.3:o:tenda:ac9_firmware:15.03.05.19\(6318\)_cn:*:*:*:*:*:*:*

More vulnerabilities in Tenda Ac9 Firmware

CVE-2025-45042 — Critical (CVSS 9.8): Tenda AC9 v15.03.05.14 was discovered to contain a command injection vulnerability via the Telnet function.
CVE-2025-44877 — Critical (CVSS 9.8): Tenda AC9 V15.03.06.42_multi was found to contain a command injection vulnerability in the formSetSambaConf function…
CVE-2025-44872 — Critical (CVSS 9.8): Tenda AC9 V15.03.06.42_multi was found to contain a command injection vulnerability in the formsetUsbUnload function…
CVE-2025-45429 — Critical (CVSS 9.8): In the Tenda ac9 v1.0 router with firmware V15.03.05.14_multi, there is a stack overflow vulnerability in…
CVE-2025-45428 — Critical (CVSS 9.8): In Tenda ac9 v1.0 with firmware V15.03.05.14_multi, the rebootTime parameter of /goform/SetSysAutoRebbotCfg has a stack…
CVE-2025-45427 — Critical (CVSS 9.8): In Tenda AC9 v1.0 with firmware V15.03.05.14_multi, the security parameter of /goform/WifiBasicSet has a stack overflow…

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