Raw vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:LSummary
CVE-2026-28420 is a medium-severity Heap-based Buffer Overflow (CWE-122) vulnerability in Vim Vim. Its CVSS base score is 4.4 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Client Execution (T1203); ranked at the 8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SI-2 (Flaw Remediation) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9088
Vulnerability Data
Vim is an open source, command line text editor. Prior to version 9.2.0076, a heap-based buffer overflow WRITE and an out-of-bounds READ exist in Vim's terminal emulator when processing maximum combining characters from Unicode supplementary planes. Version 9.2.0076 fixes the…
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issue.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Buffer overflow in client-side editor (Vim) directly enables client execution via crafted input/file.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly requires applying the vendor patch (9.2.0076) that eliminates the heap overflow and out-of-bounds read in Unicode combining-character handling.
Mandates validation of all input (here, Unicode supplementary-plane combining characters) before processing, blocking the malformed data that triggers CWE-122/CWE-125.
Process isolation limits the blast radius of a successful buffer write in the Vim terminal emulator to the isolated process only.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices directly require bounds checking and safe memory handling that prevent heap overflows.
Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.
Timely patching removes known heap-overflow instances after they exist.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development and acceptance can detect heap overflows before release.
Logging can record evidence of an out-of-bounds read but does not prevent the weakness itself.
Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.
Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.
Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.
Secure coding standards directly prescribe techniques (safe functions, bounds checks) that prevent heap-based buffer overflows.