CVE-2021-3770Public exploit

Code execution via unchecked retab value

Published Sep 6, 2021 · Updated Aug 3, 2024

Heap-based buffer overflow in Vim before 8.2.3403 allows local users to crash the editor or execute code via a crafted :retab value. The tabstop_set function converts :retab arguments with atoi and, before the patch, stores negative or oversized values without validation, leading ex_retab to access heap memory outside its allocation. Triggering requires Vim to process an attacker-supplied command, and successful memory corruption can terminate the editor or run code in the affected user context.

CVSS severity8.6
High
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Heap-based buffer overflow in Vim before 8.2.3403 allows local users to crash the editor or execute code via a crafted :retab value. The tabstop_set function converts :retab arguments with atoi and, before the patch, stores negative or oversized values without validation, leading ex_retab to access heap memory outside its allocation. Triggering requires Vim to process an attacker-supplied command, and successful memory corruption can terminate the editor or run code in the affected user context.

The record

CVE
CVE-2021-3770
Published
Sep 6, 2021
Updated
Aug 3, 2024
Vendor
Vim
Product
Vim
Classifications
CWE-122, CWE-787, T1203
Attack vector
local
Privileges
Unavailable

Timeline

How it unfolded

  1. Sep 6, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <8.2.3403

What conditions does exploitation require?

Attack vectorlocal
Required privilegesUnavailable in this record.

What is affected?

Vim · Vimversion=unspecified <8.2.3403

Published CVSS scores

8.6huntr.devCVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:C/C:H/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
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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
PrivilegesUnavailable
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-122Heap-based Buffer Overflow
CWE-787Out-of-bounds Write
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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo