How severe is CVE-2021-31627?

CVE-2021-31627 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-31627 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-31627?

CVE-2021-31627 affects Tendacn Ac9 Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-31627?

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

When was CVE-2021-31627 published?

CVE-2021-31627 was published on 2021-10-29 and last updated on 2026-07-09.

CVE-2021-31627

CVE-2021-31627 is a high-severity vulnerability in Tendacn Ac9 Firmware with a CVSS 3.x base score of 8.8. 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-120.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 5.8
EPSS exploit prediction: 1% (65th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Tendacn Ac9 Firmware
Published: 2021-10-29
Last modified: 2026-07-09

Description

Buffer Overflow vulnerability in Tenda AC9 V1.0 through V15.03.05.19(6318), and AC9 V3.0 V15.03.06.42_multi, allows attackers to execute arbitrary code via the index parameter.

Frequently asked questions

What is CVE-2021-31627?: Buffer Overflow vulnerability in Tenda AC9 V1.0 through V15.03.05.19(6318), and AC9 V3.0 V15.03.06.42_multi, allows attackers to execute arbitrary code via the index parameter.
How severe is CVE-2021-31627?: CVE-2021-31627 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-31627 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-31627?: CVE-2021-31627 affects Tendacn Ac9 Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-31627?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-31627 published?: CVE-2021-31627 was published on 2021-10-29 and last updated on 2026-07-09.

References

https://github.com/Lyc-heng/routers/blob/main/routers/stack3.md

Affected products (1)

cpe:2.3:o:tendacn:ac9_firmware:*:*:*:*:*:*:*:*

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CVE-2020-13392 — Critical (CVSS 9.8): An issue was discovered on Tenda AC6 V1.0 V15.03.05.19_multi_TD01, AC9 V1.0 V15.03.05.19(6318)_CN, AC9 V3.0…
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