# CVE-2026-73075: Vim out-of-bounds access in popup opacity handling

Source: https://junglewise.ai/threats/cve-2026-73075-vim-out-of-bounds-access-in-popup-opacity-handling  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-11. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-73075 · Severity: info · CVSS 6.2 · Published 2026-08-11

Vim is a widely-used command-line text editor. A flaw in its popup window rendering logic allows malicious Vim scripts to read and write data outside the allocated memory buffer, potentially corrupting adjacent data structures. Exploitation requires running untrusted Vim scripts or plugins, and the practical impact is undefined behavior that typically manifests silently but could lead to crashes or further compromise.

Technologies: [Vim](https://junglewise.ai/threats/technologies/vim). Vendors: [Vim](https://junglewise.ai/threats/vendors/vim).

## Quick answers

**Is CVE-2026-73075 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-73075 being exploited in the wild.

**How severe is CVE-2026-73075?** Informational severity, with a CVSS score of 6.2, published 11 August 2026.

**Which products and versions are affected?** Vim 9.2.0469 to 9.2.0842.

**Is there a fix for CVE-2026-73075?** A patch was published on 2026-07-23: Fixed in Vim 9.2.0843 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-73075 attacked?** It is attacked with local access, in an operating system.

**Am I affected by CVE-2026-73075?** Check whether you run Vim at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is an out-of-bounds read and conditional write in the popup_mark_opacity_zindex() function in src/popupwin.c. When a popup window is anchored to a text property with clipwindow and opacity options enabled, and the host window is scrolled so the anchor moves above the visible area, the popup's window row becomes negative. The function fails to bound-check this negative index before accessing a heap array, causing reads before the array's start and writes of the popup's z-index value when it is smaller than the value already present. The attack requires Vim script code that creates such a popup configuration and scrolls the host window; this cannot be triggered via file contents or modelines. The issue is fixed in Vim 9.2.0843.

## Affected products

- Vim Vim 9.2.0469 to 9.2.0842

## Timeline

- 2026-07-23: disclosed: GitHub Security Advisory GHSA-pmvp-6rcj-98p4 published
- 2026-08-11: advisory: NVD published CVE-2026-73075
- 2026-07-23: patched: Fixed in Vim 9.2.0843

## References

- [https://github.com/vim/vim/security/advisories/GHSA-pmvp-6rcj-98p4](https://github.com/vim/vim/security/advisories/GHSA-pmvp-6rcj-98p4)

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