cbcvebase.
CVE-2021-41349
published 2021-11-10

CVE-2021-41349: Microsoft Exchange Server Spoofing Vulnerability Microsoft Exchange Server Spoofing Vulnerability

medium6.5CVSS 3.1
AVNACLPRNUIRSUCHINAN
ITWEXPLOITVulnCheck KEV
Exploited in the wild
EPSS
93.88%
99.8th percentile
Microsoft Exchange Server Spoofing Vulnerability Microsoft Exchange Server Spoofing Vulnerability

Affected

10 ranges
VendorProductVersion rangeFixed in
microsoftmicrosoft_exchange_server_2013_cumulative_update_23>= 15.00.0 < 15.00.1497.02615.00.1497.026
microsoftmicrosoft_exchange_server_2016_cumulative_update_21>= 15.01.0 < 15.01.2308.02015.01.2308.020
microsoftmicrosoft_exchange_server_2016_cumulative_update_22>= 15.0.0 < 15.01.2375.01715.01.2375.017
microsoftmicrosoft_exchange_server_2019_cumulative_update_10>= 15.02.0 < 15.02.0792.01915.02.0792.019
microsoftmicrosoft_exchange_server_2019_cumulative_update_11>= 15.02.0 < 15.02.0986.01415.02.0986.014
msrcmicrosoft_exchange_server_2013_cumulative_update_23
msrcmicrosoft_exchange_server_2016_cumulative_update_21
msrcmicrosoft_exchange_server_2016_cumulative_update_22
msrcmicrosoft_exchange_server_2019_cumulative_update_10
msrcmicrosoft_exchange_server_2019_cumulative_update_11

Detection & IOCsextracted from sources · hover to see the quote

url/autodiscover/autodiscover.json
other%3Cscript%3Ealert%28document.domain%29%3B+a=%22%3C%2Fscript%3E&x=1
  • Exploit uses a POST request to /autodiscover/autodiscover.json with URL-encoded XSS payload in the body; response body should reflect 'alert(document.domain);' and 'a=""' with Content-Type text/html and HTTP 500 status.
  • Confirmed vulnerable response contains reflected strings 'alert(document.domain);' and 'a=""' in the body, Content-Type header includes 'text/html', and HTTP status is 500. A safe/patched server returns 'A potentially dangerous Request.Form value was detected from the client'.
  • Shodan queries to identify potentially exposed Microsoft Exchange servers: search for vuln:cve-2021-26855, favicon hash 1768726119, or title 'outlook'.
  • FOFA queries to identify potentially exposed Microsoft Exchange servers: title="outlook" or icon_hash=1768726119.
  • ·This CVE is distinct from CVE-2021-42305, which is a separate Microsoft Exchange Server spoofing vulnerability; ensure detection rules target the correct CVE.
  • ·Exploit status is publicly disclosed but not yet observed as exploited in the wild at time of advisory publication; however, EPSS score of 0.91098 (99.6th percentile) indicates high exploitation probability.

CVSS provenance

nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
nvdv2.04.3MEDIUMAV:N/AC:M/Au:N/C:P/I:N/A:N
cvelistv56.5MEDIUM
vulncheck6.5MEDIUM
vendor_msrc6.5MEDIUM
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