9.1 CVE-2026-55040
Enriched by CISA CISA Kev Catalog Patch Exploit
Weak authentication in Microsoft Office SharePoint allows an unauthorized attacker to bypass a security feature over a network.
https://nvd.nist.gov/vuln/detail/CVE-2026-55040
Categories
CWE-1390 : Weak Authentication
The product uses an authentication mechanism to restrict access to specific users or identities, but the mechanism does not sufficiently prove that the claimed identity is correct. Chain: e-commerce app relies on an easily-guessable timestamp (CWE-341) in a weak authentication algorithm (CWE-1390) Chain: Web UI for a Python RPC framework does not use regex anchors to validate user login emails (CWE-777), potentially allowing bypass of OAuth (CWE-1390). Chat application skips validation when Central Authentication Service(CAS) is enabled, effectively removing the second factor fromtwo-factor authentication Chain: Python-based HTTP Proxy server uses the wrong boolean operators (CWE-480) causing an incorrect comparison (CWE-697) that identifies an authN failure if all three conditions are met instead of only one, allowing bypass of the proxy authentication (CWE-1390) Distributed Control System (DCS) uses a deterministic algorithm to generate utility passwords Initialization file contains credentials that can be decoded using a "simple string transformation" UART interface for AI speaker uses empty password for root shell
References
134c704f-9b21-4f2e-91b3-4a467353bcc0 Exploit
| https://github.com/sfewer-r7/CVE-2026-55040 Exploit |
| https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-20... Exploit Third Party Advisory |
| https://www.rapid7.com/blog/post/ra-microsoft-sharepoint-jwt-token-authentica... US Government Resource |
secure@microsoft.com Patch Exploit
| https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040 Patch Vendor Advisory |
AFFECTED (from MITRE)
| Vendor | Product | Versions |
|---|---|---|
| Microsoft | Microsoft SharePoint Enterprise Server 2016 |
|
| Microsoft | Microsoft SharePoint Server 2019 |
|
| Microsoft | Microsoft SharePoint Server Subscription Edition |
|
| © 2022 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. | ||
CPE
| cpe | start | end |
|---|---|---|
| Configuration 1 | ||
| cpe:2.3:a:microsoft:sharepoint_server:*:*:*:*:subscription:*:*:* | < 16.0.19725.20434 | |
| cpe:2.3:a:microsoft:sharepoint_server:2016:*:*:*:enterprise:*:*:* | ||
| cpe:2.3:a:microsoft:sharepoint_server:2019:*:*:*:*:*:*:* | ||
REMEDIATION
Patch
| Url |
|---|
| https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-55040 |
EXPLOITS
Exploit-db.com
| id | description | date | |
|---|---|---|---|
| No known exploits | |||
POC Github
| Url |
|---|
| No known exploits |
Other Nist (github, ...)
| Url |
|---|
| https://github.com/sfewer-r7/CVE-2026-55040 |
| https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-20... |
CAPEC
Common Attack Pattern Enumerations and Classifications
| id | description | severity |
|---|---|---|
| No entry | ||
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