CVE-2021-4192Public exploit

Process crash via stale regex line pointer

Published Dec 31, 2021 · Updated Aug 3, 2024

Use-after-free in Vim before 8.2.3949 allows local users to crash the editor or trigger undefined behavior by supplying a crafted file. During /%V regular-expression matching, reg_match_visual() calls getvvcol(), which flushes rex.line, then passes the stale pointer to win_linetabsize(). A victim must source the crafted file; the demonstrated outcome is a process crash, while memory corruption can produce other undefined behavior.

CVSS severity7.8
High
EPSS probability1.72%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Vim before 8.2.3949 allows local users to crash the editor or trigger undefined behavior by supplying a crafted file. During /%V regular-expression matching, reg_match_visual() calls getvvcol(), which flushes rex.line, then passes the stale pointer to win_linetabsize(). A victim must source the crafted file; the demonstrated outcome is a process crash, while memory corruption can produce other undefined behavior.

The record

CVE
CVE-2021-4192
Published
Dec 31, 2021
Updated
Aug 3, 2024
Vendor
Vim
Product
Vim
Classifications
CWE-416, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 31, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <8.2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Vim · Vimversion=unspecified <8.2

Published CVSS scores

5.5huntr.devCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-416Use After Free
T1204.002User Execution: Malicious File

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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