Medium 5.5Published Mar 18, 2026

CVE-2026-23266fbdev: rivafb: fix divide error in nv3_arb()

Updated under an hour ago (Oct 27, 2026, 5:20 PM ET)

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: fbdev: rivafb: fix divide error in nv3_arb() A userspace program can trigger the RIVA NV3 arbitration code by calling the FBIOPUT_VSCREENINFO ioctl on /dev/fb*. When doing so, the driver recomputes FIFO arbitration parameters in nv3_arb(), using state->mclk_khz (derived from the PRAMDAC MCLK PLL) as a divisor without validating it first. In a normal setup, state->mclk_khz is provided by the real hardware and is non-zero. However, an attacker can construct a malicious or misconfigured device (e.g. a crafted/emulated PCI device) that exposes a bogus PLL configuration, causing state->mclk_khz to become zero. Once nv3_get_param() calls nv3_arb(), the division by state->mclk_khz in the gns calculation causes a divide error and crashes the kernel. Fix this by checking whether state->mclk_khz is zero and bailing out before doing the division. The following log reveals it: rivafb: setting virtual Y resolution to 2184 divide error: 0000 [#1] PREEMPT SMP KASAN PTI CPU: 0 PID: 2187 Comm: syz-executor.0 Not tainted 5.18.0-rc1+ #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014 RIP: 0010:nv3_arb drivers/video/fbdev/riva/riva_hw.c:439 [inline] RIP: 0010:nv3_get_param+0x3ab/0x13b0 drivers/video/fbdev/riva/riva_hw.c:546 Call Trace: nv3CalcArbitration.constprop.0+0x255/0x460 drivers/video/fbdev/riva/riva_hw.c:603 nv3UpdateArbitrationSettings drivers/video/fbdev/riva/riva_hw.c:637 [inline] CalcStateExt+0x447/0x1b90 drivers/video/fbdev/riva/riva_hw.c:1246 riva_load_video_mode+0x8a9/0xea0 drivers/video/fbdev/riva/fbdev.c:779 rivafb_set_par+0xc0/0x5f0 drivers/video/fbdev/riva/fbdev.c:1196 fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1033 do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1109 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1188 __x64_sys_ioctl+0x122/0x190 fs/ioctl.c:856

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: May 11, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before ec5a58f4fd581875593ea92a65485e1906a53c0f; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 52916878db2b8e3769743a94484729f0844352df; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 526460a96c5443e2fc0fd231edd1f9c49d2de26b; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 78daf5984d96edec3b920c72a93bd6821b8710b7; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 9efa0dc46270a8723c158c64afbcf1dead72b28c; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 3e4cbd1d46c246dfa684c8e9d8c20ae0b960c50a; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 73f0391e92d404da68f7484e57c106c5e673dc7e; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 before 0209e21e3c372fa2da04c39214bec0b64e4eb5f4	CNA record
linux linux_kernel linux:linux_kernel	from 2.6.12.1 before 5.10.251; from 5.11 before 5.15.201; from 5.16 before 6.1.164; from 6.2 before 6.6.127; from 6.7 before 6.12.74; from 6.13 before 6.18.13; from 6.19 before 6.19.3; 2.6.12; and 4 more ranges	NVD

References

References

https://git.kernel.org/stable/c/ec5a58f4fd581875593ea92a65485e1906a53c0f	patch
https://git.kernel.org/stable/c/52916878db2b8e3769743a94484729f0844352df	patch
https://git.kernel.org/stable/c/526460a96c5443e2fc0fd231edd1f9c49d2de26b	patch
https://git.kernel.org/stable/c/78daf5984d96edec3b920c72a93bd6821b8710b7	patch
https://git.kernel.org/stable/c/9efa0dc46270a8723c158c64afbcf1dead72b28c	patch
https://git.kernel.org/stable/c/3e4cbd1d46c246dfa684c8e9d8c20ae0b960c50a	patch
https://git.kernel.org/stable/c/73f0391e92d404da68f7484e57c106c5e673dc7e	patch
https://git.kernel.org/stable/c/0209e21e3c372fa2da04c39214bec0b64e4eb5f4	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.