CVE-2026-42897
Microsoft Exchange Server Spoofing Vulnerability
- Published
- Updated
- Reserved
- Assigned by
- microsoft
Description
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.
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as Microsoft Exchange Server Cross-Site Scripting Vulnerability.
- Added
- 15 May 2026
- Fix due (US federal)
- 29 May 2026
- Used by ransomware
- Not known
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: it is being exploited.
Timeline
ID reserved
By microsoft
- 14 days later
· 14 days later
Published
- 1 day later
· 1 day later
Added to CISA KEV
Known exploited in the wild
- 3 months later
· 3 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| microsoftCNA (assigner) | 3.1 | High8.1 | 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 |
| NVDNVD · Analyzed | 3.1 | Medium6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
- EPSS (exploitation in 30 days)
- 70.7% · top 0.6% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.1.
Weakness
Affected products
Microsoft · Microsoft Exchange Server 2016 Cumulative Update 23
- affected 15.01.0.0 – < 15.01.2507.069
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 14
- affected 15.02.0.0 – < 15.02.1544.041
Microsoft · Microsoft Exchange Server 2019 Cumulative Update 15
- affected 15.02.0.0 – < 15.02.1748.046
Microsoft · Microsoft Exchange Server Subscription Edition RTM
- affected 15.02.0.0 – < 15.02.2562.043
References (2)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-42897)Record last updated .