CVE-2026-42897Microsoft Exchange Server Spoofing Vulnerability
- 8.1HighCVSS base score
- 70.7%Exploitation in 30 daysEPSS · top 0.6% of all CVEs
- YesKnown exploitedin CISA's KEV since 15 May 2026
- YesPublic exploitsa reference or SSVC says so
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.
ENISA's EU Vulnerability Database lists it as exploited, from CISA's KEV and ENISA's EU KEV, since 15 May 2026.
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 (12 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.
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
References2
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)
- EUVD EUVD-2026-30343 (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://cveledger.app/cve/CVE-2026-42897)Record last updated .