How severe is CVE-2021-40406?

CVE-2021-40406 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-2021-40406 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-40406?

CVE-2021-40406 affects Reolink Rlc-410w Firmware. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-40406?

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-2021-40406 published?

CVE-2021-40406 was published on 2022-01-28 and last updated on 2026-06-17.

CVE-2021-40406

CVE-2021-40406 is a high-severity vulnerability in Reolink Rlc-410w 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. The underlying weakness is classified as CWE-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 7.8
EPSS exploit prediction: 2% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Reolink Rlc-410w Firmware
Published: 2022-01-28
Last modified: 2026-06-17

Description

A denial of service vulnerability exists in the cgiserver.cgi session creation functionality of reolink RLC-410W v3.0.0.136_20121102. A specially-crafted HTTP request can lead to prevent users from logging in. An attacker can send an HTTP request to trigger this vulnerability.

Frequently asked questions

What is CVE-2021-40406?: A denial of service vulnerability exists in the cgiserver.cgi session creation functionality of reolink RLC-410W v3.0.0.136_20121102. A specially-crafted HTTP request can lead to prevent users from logging in. An attacker can send an HTTP request to trigger this vulnerability.
How severe is CVE-2021-40406?: CVE-2021-40406 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-2021-40406 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-40406?: CVE-2021-40406 affects Reolink Rlc-410w Firmware. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-40406?: 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-2021-40406 published?: CVE-2021-40406 was published on 2022-01-28 and last updated on 2026-06-17.

References

https://talosintelligence.com/vulnerability_reports/TALOS-2021-1423

Affected products (1)

cpe:2.3:o:reolink:rlc-410w_firmware:3.0.0.136_20121102:*:*:*:*:*:*:*

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