CVE-2026-28421
Published: 27 February 2026
Summary
CVE-2026-28421 is a medium-severity Improper Input Validation (CWE-20) vulnerability in Vim Vim. Its CVSS base score is 5.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 1.6th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
Threat & Defense at a Glance
Threat & Defense Details
Likely Mitigating ControlsAI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Security testing and developer training directly verify and enforce proper input validation, reducing exploitability of injection and malformed-data weaknesses.
Security testing and evaluation at multiple SDLC stages directly detects missing or flawed input validation, with the required remediation process ensuring fixes are applied.
Directly implements checks on information inputs to reject invalid data before processing.
Spam protection mechanisms perform filtering and detection on inbound/outbound messages, directly compensating for missing or weak input validation of unsolicited content.
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Heap buffer overflow in Vim swap file recovery enables exploitation via crafted malicious file requiring user interaction to trigger (T1204.002), directly supporting client-side code execution or impact in a text editor application (T1203).
NVD Description
Vim is an open source, command line text editor. Versions prior to 9.2.0077 have a heap-buffer-overflow and a segmentation fault (SEGV) exist in Vim's swap file recovery logic. Both are caused by unvalidated fields read from crafted pointer blocks within…
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a swap file. Version 9.2.0077 fixes the issue.
Deeper analysisAI
CVE-2026-28421 is a vulnerability in Vim, an open source command-line text editor, affecting versions prior to 9.2.0077. It involves a heap buffer overflow and a segmentation fault in Vim's swap file recovery logic, triggered by unvalidated fields read from crafted pointer blocks within a swap file. The issues are classified under CWE-20 (Improper Input Validation) and CWE-122 (Heap-based Buffer Overflow), with a CVSS v3.1 base score of 5.3 (AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L).
An attacker with local access can exploit this vulnerability by crafting a malicious swap file and tricking a user into recovering it via Vim's recovery mechanism, which requires user interaction but no special privileges. Successful exploitation could result in limited impacts, including low-level disclosure of sensitive information, minor modification of data, or a denial of service through application crash.
Vim version 9.2.0077 addresses the vulnerability with fixes detailed in the associated GitHub commit (65c1a143c331c886dc28) and release notes. The GitHub security advisory (GHSA-r2gw-2x48-jj5p) and an oss-security mailing list post from February 27, 2026, recommend updating to the patched version to mitigate the risks.
Details
- CWE(s)