CVE-2021-3928Public exploit

Editor crash via empty spell-suggestion prefix

Published Nov 5, 2021 · Updated Aug 3, 2024

Use of uninitialized memory in Vim before 8.2.3582 allows local users to crash the editor through a crafted spell-suggestion sequence. The suggest_trie_walk function in src/spellsuggest.c backs up from an empty preword and passes memory before its buffer to spell_iswordp. A user must invoke spell suggestions on specially arranged text; the upstream regression test demonstrates the faulty path, while Debian reports no broader security impact.

CVSS severity7.8
High
EPSS probability0.64%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use of uninitialized memory in Vim before 8.2.3582 allows local users to crash the editor through a crafted spell-suggestion sequence. The suggest_trie_walk function in src/spellsuggest.c backs up from an empty preword and passes memory before its buffer to spell_iswordp. A user must invoke spell suggestions on specially arranged text; the upstream regression test demonstrates the faulty path, while Debian reports no broader security impact.

The record

CVE
CVE-2021-3928
Published
Nov 5, 2021
Updated
Aug 3, 2024
Vendor
Vim
Product
Vim
Classifications
CWE-457, CWE-908, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 5, 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 <8.2.3582

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Vim · Vimversion=unspecified <8.2.3582

Published CVSS scores

4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
7.3huntr.dev CNACVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:H
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/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-457Use of Uninitialized Variable
CWE-908Use of Uninitialized Resource
T1203Exploitation for Client Execution

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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