CVE-2020-16921 — Windows Text Services Framework Information Disclosure Vulnerability

Executive Summary

An information disclosure vulnerability exists in Text Services Framework when it fails to properly handle objects in memory. An attacker who successfully exploited this vulnerability could potentially read data that was not intended to be disclosed. Note that this vulnerability would not allow an attacker to execute code or to elevate their user rights directly, but it could be used to obtain information that could be used to try to further compromise the affected system. To exploit this vulnerability, an attacker would have to log on to an affected system and open a specially crafted file. The update addresses the vulnerability by correcting how Text Services Framework handles objects in memory.

Overview

5.5

CVSS MEDIUM

Important

MS Severity

Not Exploited

MS Exploit Status

Less Likely

MS Exploit Likelihood

Category Information Disclosure

Released Oct 13 2020

Last Updated Oct 13 2020

Publicly Disclosed No

CISA KEV Not Listed

Known Exploits None Known

EPSS Score 0.01233 — 0.65091 percentile

CVSS Vector

ATTACK VECTOR

Local

ATTACK COMPLEXITY

Low

PRIVILEGES REQUIRED

Low

USER INTERACTION

None

SCOPE

Unchanged

Temporal Score: 5.0

EPSS Score

0.01233

probability of exploitation in the next 30 days

0.65091 percentile - updated 2026-06-20

View on FIRST.org

Affected Products

23 affected products

Product	KB Article	Severity	Impact	Restart Required
Windows 10 Version 1709 for 32-bit Systems	`4580328 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1709 for ARM64-based Systems	`4580328 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1709 for x64-based Systems	`4580328 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1803 for 32-bit Systems	`4580330 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1803 for ARM64-based Systems	`4580330 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1803 for x64-based Systems	`4580330 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1809 for 32-bit Systems	`4577668 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1809 for ARM64-based Systems	`4577668 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1809 for x64-based Systems	`4577668 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1903 for 32-bit Systems	`4577671 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1903 for ARM64-based Systems	`4577671 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1903 for x64-based Systems	`4577671 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1909 for 32-bit Systems	`4577671 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1909 for ARM64-based Systems	`4577671 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 1909 for x64-based Systems	`4577671 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 2004 for 32-bit Systems	`4579311 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 2004 for ARM64-based Systems	`4579311 (Security Update)`	Important	Information Disclosure	Yes
Windows 10 Version 2004 for x64-based Systems	`4579311 (Security Update)`	Important	Information Disclosure	Yes
Windows Server 2019	`4577668 (Security Update)`	Important	Information Disclosure	Yes
Windows Server 2019 (Server Core installation)	`4577668 (Security Update)`	Important	Information Disclosure	Yes
Windows Server, version 1903 (Server Core installation)	`4577671 (Security Update)`	Important	Information Disclosure	Yes
Windows Server, version 1909 (Server Core installation)	`4577671 (Security Update)`	Important	Information Disclosure	Yes
Windows Server, version 2004 (Server Core installation)	`4579311 (Security Update)`	Important	Information Disclosure	Yes

Patches

5 patches

Article	Type	Restart
`4580328`	Security Update	Yes
`4580330`	Security Update	Yes
`4577668`	Security Update	Yes
`4577671`	Security Update	Yes
`4579311`	Security Update	Yes

Known Exploits

No known exploits have been linked for this CVE yet. When available, exploit references will be sourced from public repositories and may be unverified, incomplete, or non-functional. Always review code carefully before use in any environment.

Acknowledgments

WenQunWang of Codesafe Team of Legendsec at Qi'anxin Group

References

MSRC Advisory MITRE NVD