Crash or code execution via malformed swap recovery
Published Feb 27, 2026 · Updated Feb 27, 2026
Heap-buffer overflow in Vim before 9.2.0077 allows attackers to crash Vim or execute code through a crafted swap file. During ml_recover(), unchecked pe_bnum and pe_page_count values drive mf_get() allocation and repeated ml_append() calls, while invalid pe_old_lnum and pe_line_count values reach readfile(). Exploitation requires a user to attempt recovery from the attacker-supplied swap file; the documented outcomes are a process crash or code execution in that user's context.
Summary
What happened
Heap-buffer overflow in Vim before 9.2.0077 allows attackers to crash Vim or execute code through a crafted swap file. During ml_recover(), unchecked pe_bnum and pe_page_count values drive mf_get() allocation and repeated ml_append() calls, while invalid pe_old_lnum and pe_line_count values reach readfile(). Exploitation requires a user to attempt recovery from the attacker-supplied swap file; the documented outcomes are a process crash or code execution in that user's context.
The record
- CVE
- CVE-2026-28421
- Published
- Feb 27, 2026
- Updated
- Feb 27, 2026
- Vendor
- Vim
- Product
- Vim
- Classifications
- CWE-122, CWE-20, T1203
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 27, 2026CVE publishedPublication date reported by the CVE source.
- Feb 27, 2026Record 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.
- Affected versionversion=< 9.2.0077
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- recover-crash1.swp heap-overflow sampleproof of concept · validated
- recover-crash2.swp segmentation-fault sampleproof of concept · validated
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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