Linux Kernel up to 6.6.147/6.12.95/6.18.38/7.1.3 udmabuf kernel/dma/debug.c add_dma_entry improper synchronization

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6.2	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.147/6.12.95/6.18.38/7.1.3 and classified as critical. This vulnerability affects the function add_dma_entry of the file kernel/dma/debug.c of the component udmabuf. Executing a manipulation can lead to improper synchronization. This vulnerability appears as CVE-2026-64590. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability classified as critical was found in Linux Kernel up to 6.6.147/6.12.95/6.18.38/7.1.3. This vulnerability affects the function add_dma_entry of the file kernel/dma/debug.c of the component udmabuf. The manipulation with an unknown input leads to a improper synchronization vulnerability. The CWE definition for the vulnerability is CWE-662. The product utilizes multiple threads or processes to allow temporary access to a shared resource that can only be exclusive to one process at a time, but it does not properly synchronize these actions, which might cause simultaneous accesses of this resource by multiple threads or processes. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: dma-buf/udmabuf: skip redundant cpu sync to fix cacheline EEXIST warning When CONFIG_DMA_API_DEBUG_SG is enabled, importing a udmabuf into a DRM driver (e.g. amdgpu for video playback in GNOME Videos / Showtime) triggers a spurious warning: DMA-API: amdgpu 0000:03:00.0: cacheline tracking EEXIST, \ overlapping mappings aren't supported WARNING: kernel/dma/debug.c:619 at add_dma_entry+0x473/0x5f0 The call chain is: amdgpu_cs_ioctl -> amdgpu_ttm_backend_bind -> dma_buf_map_attachment -> [udmabuf] map_udmabuf -> get_sg_table -> dma_map_sgtable(dev, sg, direction, 0) // attrs=0 -> debug_dma_map_sg -> add_dma_entry -> EEXIST This happens because udmabuf builds a per-page scatter-gather list via sg_set_folio(). When begin_cpu_udmabuf() has already created an sg table mapped for the misc device, and an importer such as amdgpu maps the same pages for its own device via map_udmabuf(), the DMA debug infrastructure sees two active mappings whose physical addresses share cacheline boundaries and warns about the overlap. The DMA_ATTR_SKIP_CPU_SYNC flag suppresses this check in add_dma_entry() because it signals that no CPU cache maintenance is performed at map/unmap time, making the cacheline overlap harmless. All other major dma-buf exporters already pass this flag: - drm_gem_map_dma_buf() passes DMA_ATTR_SKIP_CPU_SYNC - amdgpu_dma_buf_map() passes DMA_ATTR_SKIP_CPU_SYNC The CPU sync at map/unmap time is also redundant for udmabuf: begin_cpu_udmabuf() and end_cpu_udmabuf() already perform explicit cache synchronization via dma_sync_sgtable_for_cpu/device() when CPU access is requested through the dma-buf interface. Pass DMA_ATTR_SKIP_CPU_SYNC to dma_map_sgtable() and dma_unmap_sgtable() in udmabuf to suppress the spurious warning and skip the redundant sync.

The advisory is shared for download at git.kernel.org. This vulnerability was named CVE-2026-64590 since 07/19/2026. The exploitation appears to be easy. The attack can be initiated remotely. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 333081 (Linux Distros Unpatched Vulnerability : CVE-2026-64590), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.148, 6.12.96, 6.18.39, 7.1.4 or 7.2-rc1 eliminates this vulnerability. Applying the patch 0db56e7eae932f8e2f3eb44ad1a63633d8f504f8/d6552f5cff795d60e629f37513ecf23d88fd2f82/34696563461c9a23177feb6d8aff43f4c0510278/0449a6583c0ee76778d314e4e82f166fc97fa9d8/504e2b4ab97a51d56d966cd36d0997ad30b65b2d is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at Tenable (333081). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.6.147
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
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• 6.12.91
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• 6.12.94
• 6.12.95
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
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• 6.18.36
• 6.18.37
• 6.18.38
• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
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CPE 2.2info

• 🔒
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CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
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Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Improper synchronization
CWE: CWE-662
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 333081
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-64590

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.148/6.12.96/6.18.39/7.1.4/7.2-rc1
Patch: 0db56e7eae932f8e2f3eb44ad1a63633d8f504f8/d6552f5cff795d60e629f37513ecf23d88fd2f82/34696563461c9a23177feb6d8aff43f4c0510278/0449a6583c0ee76778d314e4e82f166fc97fa9d8/504e2b4ab97a51d56d966cd36d0997ad30b65b2d

Timelineinfo

07/19/2026 CVE reserved
08/06/2026 +18 days Advisory disclosed
08/06/2026 +0 days VulDB entry created
08/06/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-64590 (🔒)
GCVE (CVE): GCVE-0-2026-64590
GCVE (VulDB): GCVE-100-386488

Entryinfo

Created: 08/06/2026 09:36
Updated: 08/06/2026 20:01
Changes: 08/06/2026 09:36 (60), 08/06/2026 20:01 (2)
Complete: 🔍
Cache ID: 216::103

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