PT-2026-58208 · Microsoft · Sharepoint Server

CVE-2026-50522 · Published 2026-05-21 · Updated 2026-07-21

Positive Technologies (AI Summary)

CVSS v2.0

10

Critical

Base vector

AV:N/AC:L/Au:N/C:C/I:C/A:C

Name of the Vulnerable Software and Affected Versions Microsoft SharePoint Server (affected versions not specified) Microsoft SharePoint Server Subscription Edition (affected versions not specified) Microsoft SharePoint Enterprise Server (affected versions not specified)

Description An issue exists in the SessionSecurityTokenHandler class due to improper verification of cryptographic signatures and unsafe deserialization of untrusted data. This allows an unauthenticated remote attacker to send a crafted request to a network-reachable component, triggering the execution of a gadget-chain (a sequence of existing code fragments used to achieve an unintended goal). Successful exploitation enables remote code execution on the server, which can lead to full environment compromise, data theft, lateral movement, and service disruption.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

DoS

RCE

Deserialization of Untrusted Data

Weakness Enumeration

CWE-502

Related Identifiers

BDU:2026-10084

CVE-2026-50522

ZDI-26-412

ZDI-26-413

Affected Products

Sharepoint Server

References · 17

• https://zerodayinitiative.com/advisories/ZDI-26-412 · Security Note
• https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-50522 · Vendor Advisory
• https://bdu.fstec.ru/vul/2026-10084 · Security Note
• http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-50522 · Security Note
• https://zerodayinitiative.com/advisories/ZDI-26-413 · Security Note
• https://nvd.nist.gov/vuln/detail/CVE-2026-50522 · Security Note
• https://twitter.com/windowsforum/status/2077206299595399394 · Twitter Post
• https://kaspersky.ru/blog/update-microsoft-patch-tuesday-july-2026-570-bugs/42283 · Note
• https://twitter.com/ET_Labs/status/2077490039290806715 · Twitter Post
• https://reddit.com/r/SecOpsDaily/comments/1v2mrnt/critical_sharepoint_rce_cve202650522_under_active · Reddit Post
• https://twitter.com/notCVE/status/2077770247168213140 · Twitter Post
• https://twitter.com/DFIR_Radar/status/2079009507234009301 · Twitter Post
• https://twitter.com/censysio/status/2078146776213655961 · Twitter Post
• https://twitter.com/UpwindMDR/status/2077285608737628369 · Twitter Post
• https://twitter.com/techepages/status/2079152871376056736 · Twitter Post