CVE-2026-98508 - Vulnerability Details

- drm/virtio: fix NULL pointer dereference on fence allocation failure

Description

In the Linux kernel, the following vulnerability has been resolved:

drm/virtio: fix NULL pointer dereference on fence allocation failure

virtio_gpu_fence_alloc() can fail due to memory pressure and return NULL,
but its caller like virtio_gpu_init_submit() never checks it. Later,
virtio_gpu_init_submit() passes the NULL fence to
virtio_gpu_fence_event_create(), which unconditionally dereferences it.

Found when fuzzing the virtio driver with Syzkaller:

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097]
CPU: 1 UID: 0 PID: 9991 Comm: syz.0.121 Not tainted 7.2.0 #4 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014
RIP: 0010:virtio_gpu_fence_event_create drivers/gpu/drm/virtio/virtgpu_submit.c:295 [inline]
RIP: 0010:virtio_gpu_init_submit drivers/gpu/drm/virtio/virtgpu_submit.c:398 [inline]
RIP: 0010:virtio_gpu_execbuffer_ioctl+0xc78/0x1aa0 drivers/gpu/drm/virtio/virtgpu_submit.c:505
Code: 85 ed 0f 85 21 09 00 00 e8 05 5a c9 fb 48 8b 44 24 10 48 8d b8 90 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 9a 0d 00 00 48 8b 44 24 10 4c 89 b0 90 00 00 00
RSP: 0018:ffffc900039dfad0 EFLAGS: 00010216
RAX: dffffc0000000000 RBX: ffffc900039dfdd8 RCX: ffffffff85f6fd3d
RDX: 0000000000000012 RSI: ffffffff85f6fd4b RDI: 0000000000000090
RBP: 0000000000000000 R0virtio_gpu_virgl_process_cmd: ctrl 0x102, error 0x1203
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880132c4000
R13: 0000000000000000 R14: ffff888073b6c700 R15: 000000000000003b
FS: 00007fab480b96c0(0000) GS:ffff8880eb6e9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007effbf5e55a8 CR3: 0000000048d19000 CR4: 0000000000350ef0
Call Trace:
<TASK>
drm_ioctl_kernel+0x1f4/0x3e0 drivers/gpu/drm/drm_ioctl.c:817
drm_ioctl+0x5f4/0xc70 drivers/gpu/drm/drm_ioctl.c:914
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fab471a82bd
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fab480b9018 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fab47435fa0 RCX: 00007fab471a82bd
RDX: 00002000000000c0 RSI: 00000000c0406442 RDI: 0000000000000003
RBP: 00007fab480b9080 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007fab47436038 R14: 00007fab47435fa0 R15: 00007ffe85ab0740
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:virtio_gpu_fence_event_create drivers/gpu/drm/virtio/virtgpu_submit.c:295 [inline]
RIP: 0010:virtio_gpu_init_submit drivers/gpu/drm/virtio/virtgpu_submit.c:398 [inline]
RIP: 0010:virtio_gpu_execbuffer_ioctl+0xc78/0x1aa0 drivers/gpu/drm/virtio/virtgpu_submit.c:505
Code: 85 ed 0f 85 21 09 00 00 e8 05 5a c9 fb 48 8b 44 24 10 48 8d b8 90 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 9a 0d 00 00 48 8b 44 24 10 4c 89 b0 90 00 00 00
RSP: 0018:ffffc900039dfad0 EFLAGS: 00010216
RAX: dffffc0000000000 RBX: ffffc900039dfdd8 RCX: ffffffff85f6fd3d
RDX: 0000000000000012 RSI: ffffffff85f6fd4b RDI: 0000000000000090
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880132c4000
R13: 0000000000000000 R14: ffff888073b6c700 R15: 000000000000003b
FS: 00007fab480b96c0(0000) GS:ffff888098ae9000(0000) knlGS:00000000
---truncated---

Published: 2026-10-18

Score: 4.7 Medium

EPSS: < 1% Very Low

KEV: No

Impact:

Action:

Analysis

Impact

The flaw originates in the virtio GPU driver of the Linux kernel, where virtio_gpu_fence_alloc() may return NULL when memory allocation fails. The calling code does not test this return value and later uses the null pointer in virtio_gpu_fence_event_create(), triggering an unconditional dereference. This results in a general protection fault that causes the kernel to panic. The bug therefore leads to a denial of service by crashing the kernel but does not enable code execution or privilege escalation.

Affected Systems

All Linux kernel releases that include the virtio GPU driver and have not yet applied the patch commit 846b3c64. This spans mainline kernels from version 4.x up through 7.2.0 and any distribution kernels shipping those releases with virtio_gpu enabled. The vulnerability exists in the virtgpu_submit module of the DRM subsystem.

Risk and Exploitability

The CVSS score of 4.7 classifies the issue as moderate severity. The EPSS score of less than 1% indicates a low probability of exploitation, and the vulnerability is not listed in CISA’s KEV catalog. Exploitation requires the ability to issue a crafted IOCTL request to the virtio GPU character device, typically from a local or guest process that can access the virtual GPU. The likely attack vector is inferred to be a malicious IOCTL call that triggers the null‑pointer dereference, causing the kernel to crash. This results in a denial of service but no arbitrary code execution or privilege escalation. The overall risk is moderate and is driven mainly by the impact of the crash rather than by exploit complexity.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`70d1ace56db6c79d39dbe9c0d5244452b67e2fde`	affected	< 9571ab7493561afb4624d69572a7ebb67d76d10f
`70d1ace56db6c79d39dbe9c0d5244452b67e2fde`	affected	< a8b83ed4a4b1d04c756f53e375e86d3881f66e72
`70d1ace56db6c79d39dbe9c0d5244452b67e2fde`	affected	< f2f1683955b95c9b958069da3050f7e8e129ff88
`70d1ace56db6c79d39dbe9c0d5244452b67e2fde`	affected	< ecced0076b700b5896e52af10d0776be8be36b0d
`70d1ace56db6c79d39dbe9c0d5244452b67e2fde`	affected	< 846b3c64fe3e77d9db20a7e3e62dbbb637c773e1
`98d3e7c5f757577394f036e0301db9e570342566`	affected	—
`4037dcd70c3335600a2a95ec6229d70859bd37a1`	affected	—
`6.1.54`	affected	< 6.2
`6.5.4`	affected	< 6.6

Linux

affected

Version	Status	Constraints
`6.6`	affected	—
`0`	unaffected	< 6.6
`6.6.158`	unaffected	≤ 6.6.*
`6.12.112`	unaffected	≤ 6.12.*
`6.18.55`	unaffected	≤ 6.18.*
`7.2.9`	unaffected	≤ 7.2.*
`7.3`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[70d1ace56db6c79d39dbe9c0d5244452b67e2fde,9571ab7493561afb4624d69572a7ebb67d76d10f)`	affected	code_commit	—
`[70d1ace56db6c79d39dbe9c0d5244452b67e2fde,a8b83ed4a4b1d04c756f53e375e86d3881f66e72)`	affected	code_commit	—
`[70d1ace56db6c79d39dbe9c0d5244452b67e2fde,f2f1683955b95c9b958069da3050f7e8e129ff88)`	affected	code_commit	—
`[70d1ace56db6c79d39dbe9c0d5244452b67e2fde,ecced0076b700b5896e52af10d0776be8be36b0d)`	affected	code_commit	—
`[70d1ace56db6c79d39dbe9c0d5244452b67e2fde,846b3c64fe3e77d9db20a7e3e62dbbb637c773e1)`	affected	code_commit	—
`98d3e7c5f757577394f036e0301db9e570342566`	affected	code_commit	—
`4037dcd70c3335600a2a95ec6229d70859bd37a1`	affected	code_commit	—
`[6.1.54,6.2)`	affected	semver	—
`[6.5.4,6.6)`	affected	semver	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`6.6`	affected	generic	—
`[0,6.6)`	unaffected	generic	—
`[6.6.158,6.7.0]`	unaffected	semver	—
`[6.12.112,6.13.0)`	unaffected	semver	—
`[6.18.55,6.19.0)`	unaffected	semver	—
`[7.2.9,7.3.0)`	unaffected	semver	—
`[7.3-rc5,*]`	unaffected	semver	—

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Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade the Linux kernel to a version that contains the fix commit 846b3c64, which removes the null‑pointer dereference in virtio_gpu_fence_alloc().
If a kernel upgrade is not immediately feasible, unload or disable the virtio GPU driver (for example, by removing the module or disabling the virtual GPU in the hypervisor configuration).
Restrict access to the virtio GPU device for untrusted users by applying udev rules or enforcing security policies that limit which users may open the device or issue IOCTL requests.

Generated by OpenCVE AI on October 20, 2026 at 12:51 UTC.

Tracking

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Advisories

Source	ID	Title
Debian DLA	DLA-4850-1	linux-6.12 security update

No CVSS v4.0

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.002.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98508.mbox
https://git.kernel.org/stable/c/846b3c64fe3e77d9db20a7e3e62dbbb637c773e1
https://git.kernel.org/stable/c/9571ab7493561afb4624d69572a7ebb67d76d10f
https://git.kernel.org/stable/c/a8b83ed4a4b1d04c756f53e375e86d3881f66e72
https://git.kernel.org/stable/c/ecced0076b700b5896e52af10d0776be8be36b0d
https://git.kernel.org/stable/c/f2f1683955b95c9b958069da3050f7e8e129ff88
https://nvd.nist.gov/vuln/detail/CVE-2026-98508
https://www.cve.org/CVERecord?id=CVE-2026-98508

History

Tue, 20 Oct 2026 00:30:00 +0000

Type	Values Removed	Values Added
References		https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98508.mbox https://nvd.nist.gov/vuln/detail/CVE-2026-98508 https://www.cve.org/CVERecord?id=CVE-2026-98508
Metrics	threat_severity `None`	cvssV3_1 `{'score': 4.7, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H'}` threat_severity `Moderate`

Mon, 19 Oct 2026 00:45:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-476

Sun, 18 Oct 2026 15:30:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: drm/virtio: fix NULL pointer dereference on fence allocation failure virtio_gpu_fence_alloc() can fail due to memory pressure and return NULL, but its caller like virtio_gpu_init_submit() never checks it. Later, virtio_gpu_init_submit() passes the NULL fence to virtio_gpu_fence_event_create(), which unconditionally dereferences it. Found when fuzzing the virtio driver with Syzkaller: Oops: general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097] CPU: 1 UID: 0 PID: 9991 Comm: syz.0.121 Not tainted 7.2.0 #4 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.17.0-0-gb52ca86e094d-prebuilt.qemu.org 04/01/2014 RIP: 0010:virtio_gpu_fence_event_create drivers/gpu/drm/virtio/virtgpu_submit.c:295 [inline] RIP: 0010:virtio_gpu_init_submit drivers/gpu/drm/virtio/virtgpu_submit.c:398 [inline] RIP: 0010:virtio_gpu_execbuffer_ioctl+0xc78/0x1aa0 drivers/gpu/drm/virtio/virtgpu_submit.c:505 Code: 85 ed 0f 85 21 09 00 00 e8 05 5a c9 fb 48 8b 44 24 10 48 8d b8 90 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 9a 0d 00 00 48 8b 44 24 10 4c 89 b0 90 00 00 00 RSP: 0018:ffffc900039dfad0 EFLAGS: 00010216 RAX: dffffc0000000000 RBX: ffffc900039dfdd8 RCX: ffffffff85f6fd3d RDX: 0000000000000012 RSI: ffffffff85f6fd4b RDI: 0000000000000090 RBP: 0000000000000000 R0virtio_gpu_virgl_process_cmd: ctrl 0x102, error 0x1203 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880132c4000 R13: 0000000000000000 R14: ffff888073b6c700 R15: 000000000000003b FS: 00007fab480b96c0(0000) GS:ffff8880eb6e9000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007effbf5e55a8 CR3: 0000000048d19000 CR4: 0000000000350ef0 Call Trace: <TASK> drm_ioctl_kernel+0x1f4/0x3e0 drivers/gpu/drm/drm_ioctl.c:817 drm_ioctl+0x5f4/0xc70 drivers/gpu/drm/drm_ioctl.c:914 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl fs/ioctl.c:583 [inline] __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x116/0x800 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fab471a82bd Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fab480b9018 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fab47435fa0 RCX: 00007fab471a82bd RDX: 00002000000000c0 RSI: 00000000c0406442 RDI: 0000000000000003 RBP: 00007fab480b9080 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 R13: 00007fab47436038 R14: 00007fab47435fa0 R15: 00007ffe85ab0740 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:virtio_gpu_fence_event_create drivers/gpu/drm/virtio/virtgpu_submit.c:295 [inline] RIP: 0010:virtio_gpu_init_submit drivers/gpu/drm/virtio/virtgpu_submit.c:398 [inline] RIP: 0010:virtio_gpu_execbuffer_ioctl+0xc78/0x1aa0 drivers/gpu/drm/virtio/virtgpu_submit.c:505 Code: 85 ed 0f 85 21 09 00 00 e8 05 5a c9 fb 48 8b 44 24 10 48 8d b8 90 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 9a 0d 00 00 48 8b 44 24 10 4c 89 b0 90 00 00 00 RSP: 0018:ffffc900039dfad0 EFLAGS: 00010216 RAX: dffffc0000000000 RBX: ffffc900039dfdd8 RCX: ffffffff85f6fd3d RDX: 0000000000000012 RSI: ffffffff85f6fd4b RDI: 0000000000000090 RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880132c4000 R13: 0000000000000000 R14: ffff888073b6c700 R15: 000000000000003b FS: 00007fab480b96c0(0000) GS:ffff888098ae9000(0000) knlGS:00000000 ---truncated---
Title		drm/virtio: fix NULL pointer dereference on fence allocation failure
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/846b3c64fe3e77d9db20a7e3e62dbbb637c773e1 https://git.kernel.org/stable/c/9571ab7493561afb4624d69572a7ebb67d76d10f https://git.kernel.org/stable/c/a8b83ed4a4b1d04c756f53e375e86d3881f66e72 https://git.kernel.org/stable/c/ecced0076b700b5896e52af10d0776be8be36b0d https://git.kernel.org/stable/c/f2f1683955b95c9b958069da3050f7e8e129ff88

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Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-10-18T15:17:15.082Z

Updated: 2026-10-19T09:20:47.221Z

Reserved: 2026-09-25T10:25:14.354Z

Link: CVE-2026-98508

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-10-18T16:17:01.947

Modified: 2026-10-19T10:19:04.167

Link: CVE-2026-98508

Redhat

Severity : Moderate

Publid Date: 2026-10-18T00:00:00Z

Links: CVE-2026-98508 - Bugzilla

OpenCVE Enrichment

Updated: 2026-10-20T13:00:12Z

Weaknesses

CWE-476
NULL Pointer Dereference

Impact

Affected Systems

Risk and Exploitability

Tracking

Attack Vector Local

Attack Complexity High

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

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