Microsoft SharePoint Server Privilege Escalation
CVE-2023-29357 is a critical-severity incorrect implementation of authentication algorithm vulnerability in Microsoft SharePoint Server 2019 from Microsoft, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 16.0.10399.20005 as the first without the flaw, so updating Microsoft SharePoint Server 2019 to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on January 10, 2024, which means attacks have been observed in the wild, including in ransomware campaigns.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Microsoft SharePoint Server 2019 to 16.0.10399.20005 or a later version.
- CISA's required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
- Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Microsoft | Microsoft SharePoint Server 2019 | 16.0.0 up to, but not including, 16.0.10399.20005 | 16.0.10399.20005 |
| Microsoft | Sharepoint Server | 2019 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (microsoft.com).
Official description
Microsoft SharePoint Server Elevation of Privilege Vulnerability
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Incorrect Implementation of Authentication Algorithm
The requirements for the product dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect.
More Incorrect Implementation of Authentication Algorithm vulnerabilities (CWE-303)
Timeline
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-29357US Government Resource
Other vulnerabilities in Microsoft SharePoint Server 2019
- 8.7 High severity
- 9.3 Critical severity
- 8.8 High severity
Microsoft SharePoint Code Injection Exploited
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