SB2026072419 - Buffer underflow in Vim

Description

This security bulletin contains information about 1 vulnerability.

1) Buffer underflow (CVE-ID: N/A)

CWE-ID: CWE-124 - Buffer Underwrite ('Buffer Underflow')

CVSSv4: 1.8 [CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]

The vulnerability allows a remote attacker to read and modify memory outside the bounds of a heap array.

The vulnerability exists due to out-of-bounds write in popup_mark_opacity_zindex() in src/popupwin.c when processing Vim script-created popup windows with the "clipwindow", "opacity", and text property anchor options after the host window is scrolled so the anchor moves above the visible area. A remote attacker can trick the victim into running a crafted Vim script to read and modify memory outside the bounds of a heap array.

The issue is not reachable by opening a file alone, because a modeline cannot call functions.

Remediation

Install update from vendor's website.

References

• https://github.com/vim/vim/security/advisories/GHSA-pmvp-6rcj-98p4
• https://github.com/vim/vim/commit/975e191dc817d8d00abca7197c4529a417c2f805