CVE-2026-55034: Microsoft SharePoint cross-site scripting in web page generation

CVE-2026-55034 · Severity: high · CVSS 7.3 · Published 2026-07-14

Microsoft SharePoint, a widely used collaboration and document management platform, is affected by a security flaw that could allow an attacker to impersonate legitimate users. By tricking a user into clicking a malicious link, an attacker with basic access to the network could steal sensitive information or perform unauthorized actions on behalf of the victim. This could lead to data breaches or unauthorized changes to corporate documents and internal sites.

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

Quick answers

Is CVE-2026-55034 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-55034 being exploited in the wild.
How severe is CVE-2026-55034?
High severity, with a CVSS score of 7.3, 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-2026-55034?
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-2026-55034 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-55034?
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 SharePoint due to improper neutralization of input during web page generation. An authenticated attacker with low privileges can exploit this 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 arbitrary script in the context of the victim's browser session. This can result in the theft of session tokens, unauthorized data access, or spoofing of user actions. Microsoft has released security updates for SharePoint Enterprise Server 2016, Server 2019, and Subscription Edition to address this issue.

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: Initial publication by Microsoft and NVD

References

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