Microsoft Exchange Server Privilege Escalation
CVE-2024-21410 is a critical-severity improper authentication vulnerability in Microsoft Exchange Server 2016 Cumulative Update 23 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 15.01.2507.037 as the first without the flaw, so updating Microsoft Exchange Server 2016 Cumulative Update 23 to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on February 15, 2024, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Microsoft Exchange Server 2016 Cumulative Update 23 to 15.01.2507.037 or a later version.
- Update Microsoft Exchange Server 2019 Cumulative Update 13 to 15.2.1544.004 or a later version.
- Update Microsoft Exchange Server 2019 Cumulative Update 14 to 15.2.1544.004 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 Exchange Server 2016 Cumulative Update 23 | 15.01.0 up to, but not including, 15.01.2507.037 | 15.01.2507.037 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 13 | 15.02.0 up to, but not including, 15.2.1544.004 | 15.2.1544.004 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 14 | 15.02.0 up to, but not including, 15.2.1544.004 | 15.2.1544.004 |
| Microsoft | Exchange Server | 2016; 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 Exchange Server Elevation of Privilege Vulnerability
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Authentication
When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct.
How developers prevent this class of flaw
- Use an authentication framework or library such as the OWASP ESAPI Authentication feature.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- 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-2024-21410US Government Resource
Other vulnerabilities in Microsoft Exchange Server 2016 Cumulative Update 23
- 9.3 Critical severity
- 9.3 Critical severity
- 8.8 High severity
- 9.6 Critical severity
- 8.1 High severity
- 6.1 Medium severity
Recent Improper Authentication vulnerabilities
- 9.8 Critical severity
- 8.1 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
- 9.8 Critical severity
Spotted an error? Tell us.