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Fencer Vulns
high 7.1

CVE-2020-16969 json

Microsoft Exchange Information Disclosure Vulnerability

published 2020-10-16 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-8927

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.7%
EPSS 2.7% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

<p>An information disclosure vulnerability exists in how Microsoft Exchange validates tokens when handling certain messages. An attacker who successfully exploited the vulnerability could use this to gain further information from a user.</p> <p>To exploit the vulnerability, an attacker could include specially crafted OWA messages that could be loaded, without warning or filtering, from the attacker-controlled URL. This callback vector provides an information disclosure tactic used in web beacons and other types of tracking systems.</p> <p>The security update corrects the way that Exchange handles these token validations.</p>

Patch / fix

Exploit prediction

2.73% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L/E:P/RL:O/RC:C
CNA 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N

Affected products

  • Microsoft Microsoft Exchange Server 2019 Cumulative Update 6
  • Microsoft Microsoft Exchange Server 2016 Cumulative Update 17
  • Microsoft Microsoft Exchange Server 2019 Cumulative Update 7
  • Microsoft Microsoft Exchange Server 2016 Cumulative Update 18
  • Microsoft Microsoft Exchange Server 2013 Cumulative Update 23

Classification

Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.