What is CVE-2024-43491?A critical-severity flaw criminals are using now.
CVE-2024-43491 is a critical-severity flaw (CVSS 9.8) in Windows 10 1507 from Microsoft, published on 10 September 2024. It is on the list of flaws known to be exploited, so criminals are already using it. The latest forecast puts its chance of use in the next 30 days at 13%. If you run an affected version, patch it first.
Published 10 September 2024. Record last updated 17 June 2026. We keep this page's data up to date.
What is CVE-2024-43491? In plain terms.
It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.
Microsoft is aware of a vulnerability in Servicing Stack that has rolled back the fixes for some vulnerabilities affecting Optional Components on Windows 10, version 1507 (initial version released July 2015). This means that an attacker could exploit these previously mitigated vulnerabilities on Windows 10, version 1507 (Windows 10 Enterprise 2015 LTSB and Windows 10 IoT Enterprise 2015 LTSB) systems that have installed the Windows security update released on March 12, 2024: KB5035858 (OS Build 10240.20526) or other updates released until August 2024. All later versions of Windows 10 are not impacted by this vulnerability. This servicing stack vulnerability is addressed by installing the September 2024 Servicing stack update (SSU KB5043936) AND the September 2024 Windows security update (KB5043083), in that order. Note: Windows 10, version 1507 reached the end of support (EOS) on May 9, 2017 for devices running the Pro, Home, Enterprise, Education, and Enterprise IoT editions. Only Windows 10 Enterprise 2015 LTSB and Windows 10 IoT Enterprise 2015 LTSB editions are still under support.
What kind of flaw is it?
- CWE-416Use After Free
How an attack on it works
Read straight from its severity rating, translated out of the shorthand.
- Where an attacker can beAnywhere on the internet
- How hard it is to pull offEasy: no special conditions
- Login needed firstNo login needed
- Does someone have to clickNo, nobody has to do anything
- What an attacker getsCan read data, change data and take it offline
Severity vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Is CVE-2024-43491 being exploited? Yes.
Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 13%.
Timeline
- Published
- Record last updated
CVE-2024-43491 scores 89. Action: Emergency patch.
We keep the score of every published flaw up to date as the evidence changes. Four things go into the score, and evidence that criminals are actually using it counts most. In order:
- Evidence it is being exploitedBiggest factor
- How severe it isStrong factor
- How widely exposed it isSmaller factor
- Threat activity around itSmaller factor
85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score.
When CVE-2024-43491 matches software you track, it lands in your list with its score and the reasons behind it.
See your own ranked list →Who is affected by CVE-2024-43491? One product.
The published record lists 1 product from 1 vendor. Versions are shown as published: "before 10.0.10240.20766" means every version up to, but not including, 10.0.10240.20766. If you run one of these, check your version, then go to the fix below.
- Operating system
Windows 10 1507
by Microsoft
Affected versionsbefore 10.0.10240.20766up to 10.0.10240.20766
How do I fix CVE-2024-43491? Four steps.
- Check whether you run itCompare your versions with the affected products above. Not sure what you run? Precursor Intelligence can work it out from your public website, or you can pick it from a list.
- Apply the vendor’s fixInstall the update named in the vendor’s advisory. We’ve put the advisory first in the list.
- If you can’t patch todayFollow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in.
- Check it wasn’t used before you patchedBecause criminals are already using this flaw, look for signs of a break-in on affected systems using the vendor’s guidance.
References
1 linkDoes CVE-2024-43491 affect you? We'll keep checking.
Looking flaws up one at a time doesn't scale. Tell us what you run once, and we tell you which flaws matter to you, in what order, and keep watching for new ones.
- Tell us what you runPick your software from a list, or let us work it out from your website.
- We match it to every flawOver 400,000 published flaws, checked against your list.
- Ranked by real-world riskA 0 to 100 score, led by evidence criminals are using it.
- Told as soon as we knowAn alert by email, in the app or by webhook to your own tools.
Free plan, no card needed. Nothing to install.
1 flaw being exploited affects software Acme tracks
Microsoft is aware of a vulnerability in Servicing Stack that has rolled back the fixes for some vulnerabilities affecting Optional Components on Windows 10,...
- Matched to
- Windows 10 1507 on Acme's software list
- What to do
- Patch first, then check for signs of use
Sent to the alert recipients Acme chose. Also in the app and to Acme's webhook.
CVE-2024-43491 is a critical-severity flaw in Windows 10 1507 from Microsoft, published on 10 September 2024. It can be attacked from anywhere on the internet without logging in, and nobody has to click anything. If it works, the attacker can read data, change data and take it offline.
It scores 9.8 out of 10 on the CVSS severity scale, which is critical. Our risk score for CVE-2024-43491 is 89 out of 100, which is Critical. Its action is "Emergency patch". Attackers are using this flaw today. If you run an affected version, it goes to the top of your list.
Attackers are already using it. It is on the government list of flaws known to be exploited, and the latest forecast puts the chance of it being used in the next 30 days at 13%.
For Windows 10 1507 from Microsoft: before 10.0.10240.20766, up to 10.0.10240.20766.
Install the update the vendor names in its advisory, linked first under "How do I fix" on this page. If you can't patch today, follow the vendor's mitigation and limit who can reach the affected system from the internet. Because criminals are already using it, also check affected systems for signs of a break-in.