Microsoft Exchange Server 2016 Cumulative…: Improper Control of Resource Identifiers
CVE-2026-62910 is a high-severity improper control of resource identifiers vulnerability in Microsoft Exchange Server 2016 Cumulative Update 23 from Microsoft, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists version 15.01.2507.072 as the first without the flaw, so updating Microsoft Exchange Server 2016 Cumulative Update 23 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1% chance of exploitation within 30 days, higher than 63% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Microsoft Exchange Server 2016 Cumulative Update 23 to 15.01.2507.072 or a later version.
- Update Microsoft Exchange Server 2019 Cumulative Update 14 to 15.02.1544.044 or a later version.
- Update Microsoft Exchange Server 2019 Cumulative Update 15 to 15.02.1748.049 or a later version.
- Read the advisory on msrc.microsoft.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Microsoft | Microsoft Exchange Server 2016 Cumulative Update 23 | 15.01.0.0 up to, but not including, 15.01.2507.072 | 15.01.2507.072 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 14 | 15.02.0.0 up to, but not including, 15.02.1544.044 | 15.02.1544.044 |
| Microsoft | Microsoft Exchange Server 2019 Cumulative Update 15 | 15.02.0.0 up to, but not including, 15.02.1748.049 | 15.02.1748.049 |
| Microsoft | Microsoft Exchange Server Subscription Edition RTM | 15.02.0.0 up to, but not including, 15.02.2562.046 | 15.02.2562.046 |
| Microsoft | Exchange Server | 2016; 2019 | Not stated |
| Microsoft | Exchange Server Subscription Edition | before 15.02.2562.046 | 15.02.2562.046 |
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
- LowA basic user account is enough.
- 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:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.2 | High | CNA (microsoft.com) |
| CVSS 3.1 | 8.8 | High | NVD |
Official description
Improper control of resource identifiers ('resource injection') in Microsoft Exchange Server allows an authorized attacker to elevate privileges over a network.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Control of Resource Identifiers
The product receives input from an upstream component, but it does not restrict or incorrectly restricts the input before it is used as an identifier for a resource that may be outside the intended control sphere.
More Improper Control of Resource Identifiers vulnerabilities (CWE-99)
Timeline
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Other vulnerabilities in Microsoft Exchange Server 2016 Cumulative Update 23
- 9.3 Critical severity
- 9.3 Critical severity
- 9.6 Critical severity
- 8.1 High severity
- 6.1 Medium severity
Recent Improper Control of Resource Identifiers vulnerabilities
- 7.3 High severity
- 9.8 Critical severity
- 9.1 Critical severity
- 9.1 Critical severity
- 7.5 High severity
- 8.8 High severity
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