How severe is CVE-2021-45739?

CVE-2021-45739 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-45739 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-45739?

CVE-2021-45739 affects Totolink A720r Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-45739?

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-2021-45739 published?

CVE-2021-45739 was published on 2022-02-04 and last updated on 2026-06-17.

CVE-2021-45739

CVE-2021-45739 is a high-severity vulnerability in Totolink A720r Firmware with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 7.8
EPSS exploit prediction: 1% (64th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Totolink A720r Firmware
Published: 2022-02-04
Last modified: 2026-06-17

Description

TOTOLINK A720R v4.1.5cu.470_B20200911 was discovered to contain a stack overflow in the Form_Login function. This vulnerability allows attackers to cause a Denial of Service (DoS) via the flag parameter.

Frequently asked questions

What is CVE-2021-45739?: TOTOLINK A720R v4.1.5cu.470_B20200911 was discovered to contain a stack overflow in the Form_Login function. This vulnerability allows attackers to cause a Denial of Service (DoS) via the flag parameter.
How severe is CVE-2021-45739?: CVE-2021-45739 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-45739 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (64th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-45739?: CVE-2021-45739 affects Totolink A720r Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-45739?: 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-2021-45739 published?: CVE-2021-45739 was published on 2022-02-04 and last updated on 2026-06-17.

References

https://github.com/pjqwudi/my_vuln/blob/main/totolink/vuln_5/5.md

Affected products (1)

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

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