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CVE-2021-4173

28
FAUCET Score

CVE-2021-4173 is a Use-After-Free vulnerability affecting Vim, as well as products from Apple and Fedora Project. This high-severity flaw (CVSS 7.8) can lead to high impact on confidentiality, integrity, and availability, requiring user interaction and local access for exploitation. Despite its severity, there is currently no evidence of active exploitation, publicly available exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 8.2.3902CPE matchmatch criteria
cpe:2.3:a:vim:vim:*:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
35CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
10.15.7CPE matchmatch criteria
cpe:2.3:o:apple:mac_os_x:10.15.7:*:*:*:*:*:*:*
10.15.7CPE matchmatch criteria
cpe:2.3:o:apple:mac_os_x:10.15.7:security_update_2020-001:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

6.8MEDIUM

CVSS:3.0/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:H/A:H

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.3
Impact Score
5.5
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.62%
Probability of exploitation in next 30 days
EPSS Percentile
73.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0162 is in the 72nd percentile among its peer group of 11,621 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (10)

github_advisorypatch availablevia nvd_reference
View patch
microsoftpatch availablevia msrc
Product: 18930-16820Fixed in: 8.2.4006-1
microsoftpatch availablevia msrc
Product: 18812-16823Fixed in: 8.2.4081-1
microsoftpatch availablevia msrc
Product: cm1 vim 8.2.4006-1 on CBL Mariner 1.0Fixed in: 8.2.4006-1
microsoftpatch availablevia msrc
Product: cbl2 vim 8.2.4081-1 on CBL Mariner 2.0Fixed in: 8.2.4081-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 8.2.4006-1
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 8.2.4006-1
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 x64Fixed in: 8.2.4081-1
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 ARMFixed in: 8.2.4081-1
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 9Fixed in: vim

Vendor Advisories (3)

microsoft2022-Jan/CVE-2021-4173

CVE-2021-4173

Jan 11, 2022
redhatCVE-2021-4173Low

vim: use-after-free with nested :def function

Dec 27, 2021
microsoft2021-Dec/CVE-2021-4173Important

Use After Free in vim/vim

Dec 14, 2021

References

lists.debian.org / debian-lts-announce/2025/03/msg00023.html
seclists.org / fulldisclosure/2022/Jul/14
Mailing ListThird Party Advisory
seclists.org / fulldisclosure/2022/Mar/29
Mailing ListThird Party Advisory
seclists.org / fulldisclosure/2022/May/35
Mailing ListThird Party Advisory
github.com / vim/vim/commit/9c23f9bb5fe435b28245ba8ac65aa0ca6b902c04
PatchThird Party Advisory
huntr.dev / bounties/a1b236b9-89fb-4ccf-9689-ba11b471e766
ExploitThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/2EY2VFBU3YGGWI5BW4XKT3F37MYGEQUD
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/3FH2J57GDA2WMBS6J56F6QQRA6BXQQFZ
security.gentoo.org / glsa/202208-32
Third Party Advisory
support.apple.com / kb/HT213183
Release NotesThird Party Advisory
support.apple.com / kb/HT213256
Third Party Advisory
support.apple.com / kb/HT213343
Third Party Advisory
openwall.com / lists/oss-security/2022/01/15/1
Mailing ListThird Party Advisory