CVE-2021-40506

Name: CVE-2021-40506
Creator: NVD / NIST
Published: 2023-04-18T12:15:07.15+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 0.73%

Last modified Jun 17, 2026

CVE-2021-40506 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 0.73% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

0.73%

49.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Openrisc	Or1200 Firmware	>= 2011-09-10, <= 2015-11-11

References

https://github.com/openrisc/or1200/commit/2c0765d7ba12813df273cd693a99c4e744f0fbd5Patch
https://seth.engr.tamu.edu/software-releases/thehuzz/Third Party Advisory
https://github.com/openrisc/or1200/commit/2c0765d7ba12813df273cd693a99c4e744f0fbd5Patch
https://seth.engr.tamu.edu/software-releases/thehuzz/Third Party Advisory

Timeline

Published: Apr 18, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-40506?

How severe is CVE-2021-40506?

CVE-2021-40506 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.73% probability of exploitation in the next 30 days.

How do I fix CVE-2021-40506?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-40506?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST