CVE-2023-4738Public exploit

Memory corruption via unchecked substitution result length

Published Sep 2, 2023 · Updated Nov 3, 2025

Heap-based buffer overflow in Vim before 9.0.1848 allows local users to corrupt memory by processing a crafted Vim script. The vim_regsub_both function copies an evaluated substitution result into a destination buffer without confirming that it fits the remaining capacity. A user must open or source crafted content, and the upstream regression test demonstrates a Vim process crash.

CVSS severity7.8
High
EPSS probability0.60%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer overflow in Vim before 9.0.1848 allows local users to corrupt memory by processing a crafted Vim script. The vim_regsub_both function copies an evaluated substitution result into a destination buffer without confirming that it fits the remaining capacity. A user must open or source crafted content, and the upstream regression test demonstrates a Vim process crash.

The record

CVE
CVE-2023-4738
Published
Sep 2, 2023
Updated
Nov 3, 2025
Vendor
Vim
Product
Vim
Classifications
CWE-787, CWE-122, T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 2, 2023CVE publishedPublication date reported by the CVE source.
  2. Nov 3, 2025Record 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 <9.0.1848

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Vim · Vimversion=unspecified <9.0.1848

Published CVSS scores

7.8huntr.devCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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-787Out-of-bounds Write
CWE-122Heap-based Buffer Overflow
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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