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CVE-2021-47641

5.5 · MEDIUM

In the Linux kernel, the following vulnerability has been resolved: video: fbdev: cirrusfb: check pixclock to avoid divide by zero Do a sanity check on pixclock value to avoid divide by zero.

Published Feb 26, 2025CWE-369EPSS 0.25%

Overview

CVE-2021-47641 is a medium-severity vulnerability. It was published on February 26, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

Technical description

In the Linux kernel, the following vulnerability has been resolved:

video: fbdev: cirrusfb: check pixclock to avoid divide by zero

Do a sanity check on pixclock value to avoid divide by zero.

If the pixclock value is zero, the cirrusfb driver will round up

pixclock to get the derived frequency as close to maxclock as

possible.

Syzkaller reported a divide error in cirrusfb_check_pixclock.

divide error: 0000 [#1] SMP KASAN PTI

CPU: 0 PID: 14938 Comm: cirrusfb_test Not tainted 5.15.0-rc6 #1

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2

RIP: 0010:cirrusfb_check_var+0x6f1/0x1260

Call Trace:

fb_set_var+0x398/0xf90

do_fb_ioctl+0x4b8/0x6f0

fb_ioctl+0xeb/0x130

__x64_sys_ioctl+0x19d/0x220

do_syscall_64+0x3a/0x80

entry_SYSCALL_64_after_hwframe+0x44/0xae

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/1d3fb46439ad4e8f0c5739eb33d1875ac9e0f135Refgit.kernel.org/stable/c/40b13e3d85744210db13457785646634e2d056bdRefgit.kernel.org/stable/c/45800c42ef000f417270bcfc08630e42486fca99Refgit.kernel.org/stable/c/53a2088a396cfa1da92690a1da289634cd73bf0dRefgit.kernel.org/stable/c/5c6f402bdcf9e7239c6bc7087eda71ac99b31379Refgit.kernel.org/stable/c/6fe23ff94e7840097202e85c148688940b37c9b1Refgit.kernel.org/stable/c/8c7e2141fb89c620ab4e41512e262fbf25b8260dRefgit.kernel.org/stable/c/c656d04247a2654ede5cead2ecbf83431dad5261Refgit.kernel.org/stable/c/e498b504f8c81b07efab9febf8503448de4dc9cf

How CyberStrike helps

Frequently asked questions

What is CVE-2021-47641?

CVE-2021-47641 is a medium-severity vulnerability. It was published on February 26, 2025 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2021-47641?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-47641?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-47641?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-47641 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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