What is the CVSS score of CVE-2021-45756?

CVE-2021-45756 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 1.7%.

Is there a public PoC exploit available for CVE-2021-45756?

Yes, a public proof-of-concept exploit is available for CVE-2021-45756. Prioritise patching immediately. EPSS: 1.7%.

Rt Ac68U Firmware CVE-2021-45756

Q: Which versions of Rt Ac68U Firmware are affected by 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.

CRITICAL

Classic Buffer Overflow (CWE-120)

2022-03-23 cve@mitre.org

Buffer Overflow Rt Ac68U Firmware Rt Ac5300 Firmware Asus

9.8

CVSS 3.1 · NVD

View

Vulnerability Assessment

Weakness	CWE CWE-120 ASVS 5.0 V15 - Secure Coding and Architecture Buffer copy size validation MITRE ATT&CK 1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 9.8 (CRITICAL). Attack characteristics: network attack vector, low complexity, no privileges required, no user interaction not required. Public proof-of-concept exploit code is available. EPSS exploitation probability: 1.74%.
Exploit ScenarioDerived	A remote attacker could overflow a buffer to corrupt adjacent memory by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

Act Now Prioritize within 24-48h. Why: CRITICAL severity + public POC available.

No patch listed yet 1.7% exploitation probability (EPSS)

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AnalysisAI

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. Rated critical severity (CVSS 9.8), this vulnerability is remotely exploitable, no authentication required, low attack complexity. Public exploit code available and no vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Always validate buffer sizes before copy operations. Use bounded functions (strncpy, snprintf). Enable compiler protections.

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Buffer Copy without Size Check (CWE-120), which allows attackers to overflow a buffer to corrupt adjacent memory. 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. Affected products include: Asus Rt-Ac68U Firmware, Asus Rt-Ac5300 Firmware.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

DescriptionNVD

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.

Threat Intelligence Overview

EPSS Score

1.7%

Top 25% exploitable

Exploit

POC

Public exploit code exists

Data Quality

5 sources

Confidence: Medium

NVD

CVE.org

EPSS

GitHub

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity CRITICAL

CISA KEV No

Public POC Yes

EPSS 1.7%

Patch available No

Active threat No

Deciding rule

CRITICAL severity + public POC available

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +2

CVSS: +49

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.