Medium [CVE-2026-57451] Denial of service via crafted undo file
This medium-severity Red Hat Linux advisory covers CVE-2026-57451 affecting Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4, Red Hat package: vim.
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Summary
Vim is an open source, command line text editor. Prior to 9.2.0670, get_text_props() in src/textprop.c reads a uint16 property count stored inline after a line's text and returns it as the number of 32-byte textprop_T entries that follow.
The only check is a floor that guarantees room for a single entry; the count is never checked against the amount of data actually present. A line that declares a large count while carrying little data causes consumers to read far past the end of the line buffer.
Such a line can be delivered through a crafted undo file, leading to a crash. This vulnerability is fixed in 9.2.0670.
A flaw in Vim allows an attacker to cause a Denial of Service (DoS) via an application crash. If a user opens a maliciously crafted undo file, an out-of-bounds read is triggered in the get_text_props() function due to missing length validation on property counts.
Exploitation requires specific user interaction; the vulnerability only triggers when a local user is tricked into opening a specially crafted undo file in Vim. This limits the attack surface to scenarios where untrusted files are intentionally processed Red Hat severity: Moderate — CVSS 5.5 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H).
Weakness: CWE-125. Affected Red Hat products: Red Hat Enterprise Linux 9; Red Hat OpenShift Container Platform 4.
- < 9.2.0670
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
- 9.2.0670
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
Mitigation checklist
- Users are advised to avoid opening or processing undo files from untrusted or unknown sources. If your team compiles Vim from source, ensure standard compiler security flags (like -D_FORTIFY_SOURCE=2 or 3) are enabled. This provides a safety net by detecting out-of-bounds reads and safely terminating the application before exploitation can occur.
Official advisory · high-confidence parse· fetched 12 days ago·verify at source
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