How severe is CVE-2021-45756?

CVE-2021-45756 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-2021-45756 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-45756?

CVE-2021-45756 primarily affects Asus Rt-ac68u 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-2021-45756?

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-2021-45756 published?

CVE-2021-45756 was published on 2022-03-23 and last updated on 2026-07-05.

CVE-2021-45756

Q: What is CVE-2021-45756?

Asus RT-AC68U <3.0.0.4.385.20633 and RT-AC5300 <3.0.0.4.384.82072 are affected by a buffer overflow in blocking_request.cgi.

CVE-2021-45756 is a critical-severity vulnerability in Asus Rt-ac68u 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-120.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-120
Affected product: Asus Rt-ac68u Firmware
Published: 2022-03-23
Last modified: 2026-07-05

Description

Asus RT-AC68U <3.0.0.4.385.20633 and RT-AC5300 <3.0.0.4.384.82072 are affected by a buffer overflow in blocking_request.cgi.

Frequently asked questions

What is CVE-2021-45756?: Asus RT-AC68U <3.0.0.4.385.20633 and RT-AC5300 <3.0.0.4.384.82072 are affected by a buffer overflow in blocking_request.cgi.
How severe is CVE-2021-45756?: CVE-2021-45756 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-2021-45756 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-45756?: CVE-2021-45756 primarily affects Asus Rt-ac68u 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-2021-45756?: 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-2021-45756 published?: CVE-2021-45756 was published on 2022-03-23 and last updated on 2026-07-05.

References

Affected products (2)

cpe:2.3:o:asus:rt-ac68u_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:asus:rt-ac5300_firmware:*:*:*:*:*:*:*:*

More vulnerabilities in Asus Rt-ac68u Firmware

CVE-2018-9285 — Critical (CVSS 9.8): Main_Analysis_Content.asp in /apply.cgi on ASUS RT-AC66U, RT-AC68U, RT-AC86U, RT-AC88U, RT-AC1900, RT-AC2900, and…
CVE-2021-37317 — Critical (CVSS 9.1): Directory Traversal vulnerability in Cloud Disk in ASUS RT-AC68U router firmware version before 3.0.0.4.386.41634…
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