Is CVE-2021-40506 actively exploited?

No active exploitation of CVE-2021-40506 has been confirmed so far. Continue monitoring, as exploit status can change.

Can CVE-2021-40506 be exploited remotely?

Yes. CVE-2021-40506 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2021-40506?

CVE-2021-40506 has a CVSS score of 9.8 (CRITICAL).

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CRITICAL

CVE-2021-40506

CWE-287Published: April 18, 2023· Updated: Jun 17, 2026

9.8

CVSS v3.1

Official Description

An issue was discovered in the ALU unit of the OR1200 (aka OpenRISC 1200) processor 2011-09-10 through 2015-11-11. The overflow flag is not being updated for the msb and mac instructions, which results in an incorrect value in the overflow flag. Any software that relies on this flag may experience corruption in execution.

NVD Source

Risk Analysis

A flaw in the OR1200 processor ALU unit causes the overflow flag to fail to update for specific instructions, leading to potential execution corruption. This is classified as critical due to the impact on system integrity. It is not currently tracked in the CISA KEV.

No public exploit is known for this vulnerability, and it is not in KEV. The flaw is remotely exploitable with low attack complexity.

Recommended Action

Apply firmware updates if provided by the vendor. Developers should avoid relying on the overflow flag for critical logic in affected environments.

Generated by the CTIWATCH analysis pipeline from this CVE's metadata (CVSS, EPSS, KEV status, exploit intelligence). Verify against vendor advisories before acting.

Technical Analysis

CVE-2021-40506 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 9.8.

From a weakness classification perspective (CWE-287): Authentication bypass vulnerabilities allow attackers to access protected resources without valid credentials.