CVE-2026-55020: Microsoft SharePoint cross-site scripting vulnerability

CVE-2026-55020 · Severity: medium · CVSS 4.6 · Published 2026-07-14

Microsoft SharePoint, a widely used platform for document management and team collaboration, is affected by a security flaw that could allow an attacker to perform spoofing. An authorized user could trick another person into interacting with malicious content, potentially leading to unauthorized actions or the theft of sensitive information within the SharePoint environment. This could compromise the integrity of internal communications and data.

Technologies: Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019, Microsoft SharePoint Server Subscription Edition. Vendors: Microsoft.

Quick answers

Is CVE-2026-55020 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55020 being exploited in the wild.
How severe is CVE-2026-55020?
Medium severity, with a CVSS score of 4.6, published 14 July 2026.
Which products and versions are affected?
Microsoft SharePoint Enterprise Server 2016 16.0.0 to 16.0.5561.1001; Microsoft SharePoint Server 2019 16.0.0 to 16.0.10417.20175; Microsoft SharePoint Server Subscription Edition 16.0.0 to 16.0.19725.20434.
Is there a fix for CVE-2026-55020?
No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-55020 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-55020?
Check whether you run Microsoft SharePoint Enterprise Server 2016, Microsoft SharePoint Server 2019 or Microsoft SharePoint Server Subscription Edition at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A cross-site scripting (XSS) vulnerability exists in Microsoft Office SharePoint due to improper neutralization of input during web page generation. An authenticated attacker with low privileges can exploit this flaw by sending a specially crafted request to a vulnerable SharePoint server. Successful exploitation requires a victim to interact with a malicious link or page, allowing the attacker to execute scripts in the context of the victim's browser session. This can lead to spoofing, session hijacking, or unauthorized data access. Microsoft has released security updates to address this issue across affected versions of SharePoint Server.

Affected products

  • Microsoft SharePoint Enterprise Server 2016 16.0.0 to 16.0.5561.1001
  • Microsoft SharePoint Server 2019 16.0.0 to 16.0.10417.20175
  • Microsoft SharePoint Server Subscription Edition 16.0.0 to 16.0.19725.20434

Timeline

  • 2026-07-14: advisory: Microsoft released the security advisory and patches.
  • 2026-07-14: disclosed: CVE-2026-55020 was published to the NVD.

References

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