CVE-2026-42897Microsoft Exchange Server Spoofing Vulnerability
Updated under an hour ago ()
Does this affect you?
It affects Microsoft Exchange Server 2016 Cumulative Update 23 and 5 other products. Add what you run to find out whether that includes you.
CISA lists it as known exploited since May 15, 2026; federal agencies had to remediate by May 29, 2026. Treat that date as your deadline.
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Improper neutralization of input during web page generation ('cross-site scripting') in Microsoft Exchange Server allows an unauthorized attacker to perform spoofing over a network.
- CVSS
- 8.1 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N/E:F/RL:O/RC:C
- Weakness (CWE)
- CWE-79
- Known exploited
- Added to CISA KEV May 15, 2026; federal remediation due May 29, 2026Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
- EPSS (exploitation in the next 30 days)
- 0.52% (percentile 43)
- Assigned by
- microsoft
- NVD analysis
- Analyzed
- Record last updated
- Aug 10, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Microsoft Microsoft Exchange Server 2016 Cumulative Update 23 microsoft:exchange_server_2016_cumulative_update_23 (from the name) | from 15.01.0.0 before 15.01.2507.069 | CNA record |
Microsoft Microsoft Exchange Server 2019 Cumulative Update 14 microsoft:exchange_server_2019_cumulative_update_14 (from the name) | from 15.02.0.0 before 15.02.1544.041 | CNA record |
Microsoft Microsoft Exchange Server 2019 Cumulative Update 15 microsoft:exchange_server_2019_cumulative_update_15 (from the name) | from 15.02.0.0 before 15.02.1748.046 | CNA record |
Microsoft Microsoft Exchange Server Subscription Edition RTM microsoft:exchange_server_subscription_edition_rtm (from the name) | from 15.02.0.0 before 15.02.2562.043 | CNA record |
microsoft exchange_server microsoft:exchange_server | 2016; 2016; 2016; 2016; 2016; 2016; 2016; 2016; and 31 more ranges | NVD |
microsoft exchange_server_subscription_edition microsoft:exchange_server_subscription_edition | before 15.02.2562.043 | NVD |
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-42897vendor-advisory, patch, mitigation
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-42897us-government-resource
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.