# What is CVE-2025-53771? > CVE-2025-53771 is a medium-severity flaw (CVSS 6.5) in SharePoint Server from Microsoft, published on 20 July 2025. It is not on the list of flaws known to be exploited today. The latest forecast puts its chance of use in the next 30 days at over 99%. If you run an affected version, plan in the vendor’s fix. Canonical page: https://www.precursorintelligence.com/what-is/cve-2025-53771 ## At a glance - **Verdict:** Fix this soon. Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month. - **Precursor Intelligence risk score:** 75 out of 100 (High); action: Patch now. Kept up to date as the evidence changes. - **Severity:** Medium (CVSS 6.5 out of 10) - **Known to be exploited:** No, not on the list of flaws known to be exploited today - **Chance of use in the next 30 days:** over 99% (latest exploit-likelihood forecast) - **Published:** 20 July 2025 - **Record last updated:** 14 August 2025 - **Main product:** SharePoint Server from Microsoft - **Affected products:** 1 ## What is CVE-2025-53771? 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 some data and change some data. ### The official description Improper authentication in Microsoft Office SharePoint allows an unauthorized attacker to perform spoofing over a network. ### What kind of flaw is it? - CWE-287: Improper Authentication ### How an attack on it works - Where an attacker can be: Anywhere on the internet - How hard it is to pull off: Easy: no special conditions - Login needed first: No login needed - Does someone have to click: No, nobody has to do anything - What an attacker gets: Can read some data and change some data Severity vector: `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N` ## Is CVE-2025-53771 being exploited? Not that we know of It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at over 99%. That can change at any time, which is why we keep watching. Exploit likelihood over the last 7 days: >99%, >99%, >99%, >99%, >99%, >99%, >99%. ### Timeline - 20 July 2025: Published - 8 August 2025: Exploit likelihood jumped - 14 August 2025: Record last updated - 1 April 2026: Exploit likelihood fell ### How Precursor Intelligence ranks it CVE-2025-53771 scores **75 out of 100 (High)**, with the action "Patch now". Every published flaw gets a risk score from 0 to 100, kept up to date as the evidence changes. Four things go into the score, from the one that counts most to the ones that count less: - Evidence it is being exploited: biggest factor - How severe it is: strong factor - How widely exposed it is: smaller factor - Threat activity around it: smaller factor 85 and above is Critical. Anything confirmed as exploited is always marked for an emergency patch, whatever its score. When this flaw matches software you track, it lands in your list with its score and the reasons behind it. ## Who is affected by CVE-2025-53771? The published record lists 1 product. Versions are as published: "before 16.0.18526.20508" means every version up to, but not including, 16.0.18526.20508. - [SharePoint Server](https://www.precursorintelligence.com/product/microsoft/sharepoint_server) by [Microsoft](https://www.precursorintelligence.com/vendors/microsoft) (Application): before 16.0.18526.20508, 2016, 2019 ## How do I fix CVE-2025-53771? 1. **Check whether you run it.** Compare 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. 2. **Apply the vendor’s fix.** Install the update named in the vendor’s advisory. We’ve put the advisory first in the list. 3. **If you can’t patch today.** Follow any mitigation the vendor publishes, and limit who can reach the affected system from the internet until the update is in. 4. **Keep an eye on it.** Track the product and we tell you as soon as we spot this flaw on the list of exploited flaws, or a jump in its exploit likelihood. ### References - [msrc.microsoft.com](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53771) (Vendor advisory) - [bleepingcomputer.com](https://www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-exploited-in-rce-attacks-no-patch-available/) (Press/media coverage) ## Questions ### What is CVE-2025-53771? CVE-2025-53771 is a medium-severity flaw in SharePoint Server from Microsoft, published on 20 July 2025. 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 some data and change some data. ### How serious is CVE-2025-53771? It scores 6.5 out of 10 on the CVSS severity scale, which is medium. Our risk score for CVE-2025-53771 is 75 out of 100, which is High. Its action is "Patch now". Not confirmed as exploited yet, but serious or likely enough that it should not wait for a quiet month. ### Is CVE-2025-53771 being exploited? It is not on the list of flaws known to be exploited today. The latest forecast puts the chance of it being used in the next 30 days at over 99%. That can change at any time, which is why we keep watching. ### Which versions does CVE-2025-53771 affect? For SharePoint Server from Microsoft: before 16.0.18526.20508, 2016, 2019. ### How do I fix CVE-2025-53771? 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. ## Does CVE-2025-53771 affect you? Precursor Intelligence keeps checking for you: - **Tell us what you run.** Pick your software from a list, or let us work it out from your website. - **We match it to every flaw.** Over 400,000 published flaws, checked against your list. - **Ranked by real-world risk.** Every flaw gets a 0 to 100 risk score, kept up to date, led by evidence criminals are using it. - **Told as soon as we know.** An alert by email, in the app or by webhook to your own tools. Start free (no card, nothing to install): https://www.precursorintelligence.com/register Book a demo: https://www.precursorintelligence.com/contact