# CVE-2026-89806: drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation

CVE-2026-89806 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-89806, released September 23, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-89806
- Priority: High
- CVSS: 8.4 (Important)
- EPSS: 0.0019
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 16, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-89806

## Description

In the Linux kernel, the following vulnerability has been resolved:  drm/sysfb: ofdrm: Fix integer overflow in fb_size calculation  The framebuffer size calculation `fb_size = linebytes * height` can overflow when both values are large (e.g., 46341 * 46341 > INT_MAX). Since linebytes and height are both int types, the multiplication is performed as int * int, which results in undefined behavior on overflow.  Use check_mul_overflow() to detect and prevent this overflow, consistent with the approach used in simpledrm.c and corebootdrm.c.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.113-1 | [DEBIAN-CVE-2026-89806](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89806.md) | Sep 23, 2026 |
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-89806](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89806.md) | Sep 23, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.113-1~deb12u1 | [DEBIAN-CVE-2026-89806](https://patchblox.com/security/data/fix/linux/debian-cve-2026-89806.md) | Sep 23, 2026 |

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Data as of 2026-11-08T19:12:23Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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