CVE-2026-98142: Linux kernel · drm/cirrus-qemu: Validate BAR0 size during probe
Source GCVE Database
Not known to be exploited · CVSS 5.5 High · fixed in 92312d333bf700798f92f30406c721bce87506f3 : patch Linux kernel soon.
Data as of 27 Oct 2026, 19:27 UTC
- Patch
- Available – fixed in 92312d333bf700798f92f30406c721bce87506f3, 144f51cd0ccc3ad47a6099917b7bb535611fb18f, 26bd90c886218f36c9adeab206b0e27b4384e2f6 +2
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in– |
Description
In the Linux kernel, the following vulnerability has been resolved: drm/cirrus-qemu: Validate BAR0 size during probe The `cirrus-qemu` driver relies on `CIRRUS_VRAM_SIZE` (4 MB) to validate framebuffer sizes. However, during PCI probe, the driver mapped BAR0 without verifying that its size matches `CIRRUS_VRAM_SIZE`. If a PCI device with a BAR0 smaller than 4 MB is bound to the driver, the mapped VRAM will be smaller than expected. Because validation checks assume 4 MB VRAM, framebuffers larger than the mapped memory can be created. When the display plane is updated (e.g. during release), `cirrus_primary_plane_helper_atomic_update()` copies the framebuffer to VRAM using `drm_fb_memcpy()`. Writing past the end of the mapped I/O memory causes a supervisor write page fault: BUG: unable to handle page fault for address: ffffc9000389c000 ... RIP: 0010:memcpy_toio+0x7c/0xe0 arch/x86/lib/iomem.c:110 ... Call Trace: <TASK> iosys_map_memcpy_to include/linux/iosys-map.h:285 [inline] drm_fb_memcpy+0x325/0x5d0 drivers/gpu/drm/drm_format_helper.c:442 cirrus_primary_plane_helper_atomic_update+0x98a/0xb00 drivers/gpu/drm/tiny/cirrus-qemu.c:358 drm_atomic_helper_commit_planes+0x626/0xea0 drivers/gpu/drm/drm_atomic_helper.c:3038 drm_atomic_helper_commit_tail+0x60/0x510 drivers/gpu/drm/drm_atomic_helper.c:1989 commit_tail+0x2b1/0x3c0 drivers/gpu/drm/drm_atomic_helper.c:2074 drm_atomic_helper_commit+0xa77/0xb10 drivers/gpu/drm/drm_atomic_helper.c:2312 Fix this by validating in `cirrus_pci_probe()` that the PCI BAR0 resource is not less than `CIRRUS_VRAM_SIZE`, returning `-ENODEV` if it is less.
References
- nvd.nist.gov/vuln/detail/CVE-2026-98142 (opens in a new tab)
- git.kernel.org/stable/c/0b5084a1f070ad1fc34e11945644ae034bbc774c (opens in a new tab)
- git.kernel.org/stable/c/144f51cd0ccc3ad47a6099917b7bb535611fb18f (opens in a new tab)
- git.kernel.org/stable/c/26bd90c886218f36c9adeab206b0e27b4384e2f6 (opens in a new tab)
- git.kernel.org/stable/c/2a0e7bcff3fa63e7309d2b39e18af59eb8ef2b6e (opens in a new tab)
- git.kernel.org/stable/c/92312d333bf700798f92f30406c721bce87506f3 (opens in a new tab)