Linux Kernel up to 6.18.38/7.1.3 iommufd iommufd_veventq_fops_read data_len buffer overflow

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
9.5	$5k-$25k	0.00

Summaryinfo

A vulnerability categorized as very critical has been discovered in Linux Kernel up to 6.18.38/7.1.3. This issue affects the function iommufd_veventq_fops_read of the component iommufd. Such manipulation of the argument data_len leads to buffer overflow. This vulnerability is referenced as CVE-2026-64293. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.18.38/7.1.3 and classified as very critical. Affected by this issue is the function iommufd_veventq_fops_read of the component iommufd. The manipulation of the argument data_len with an unknown input leads to a buffer overflow vulnerability. Using CWE to declare the problem leads to CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. Impacted is confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: iommufd: Use sizeof(*hdr) instead of sizeof(hdr) in veventq read The bound-check in iommufd_veventq_fops_read() for the normal vEVENT path uses sizeof(hdr) where the surrounding code uses sizeof(*hdr): if (!vevent_for_lost_events_header(cur) && sizeof(hdr) + cur->data_len > count - done) { hdr is declared as struct iommufd_vevent_header *, so sizeof(hdr) evaluates to the size of the pointer. Surrounding code uses sizeof(*hdr) consistently: if (done >= count || sizeof(*hdr) > count - done) { ... if (copy_to_user(buf + done, hdr, sizeof(*hdr))) { ... done += sizeof(*hdr); struct iommufd_vevent_header is currently 8 bytes (two __u32 fields, flags and sequence), so on 64-bit (sizeof(void *) == 8) the two expressions happen to be equal and the check works as intended. On 32-bit (sizeof(void *) == 4) the check under-counts the header by 4 bytes: a vEVENT whose data_len causes 8 + cur->data_len to exceed count - done while 4 + cur->data_len does not will pass the check, then the loop will copy_to_user 8 bytes of header followed by data_len bytes of payload, writing past the user-supplied buffer. It is also a latent bug for any future expansion of struct iommufd_vevent_header beyond sizeof(void *) on 64-bit; the check should not depend on the type happening to match the host pointer width. Use sizeof(*hdr) to match the rest of the function and the actual amount that will be copied.

The advisory is available at git.kernel.org. This vulnerability is handled as CVE-2026-64293 since 07/19/2026. The exploitation is known to be easy. The attack may be launched remotely. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $5k-$25k at the moment (estimation calculated on 07/27/2026).

The vulnerability scanner Nessus provides a plugin with the ID 329906 (Linux Distros Unpatched Vulnerability : CVE-2026-64293), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.18.39, 7.1.4 or 7.2-rc1 eliminates this vulnerability. Applying the patch 04a177f91160ee18da98f5689482cf0f589ec869/0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72/be93d186ae88a92e7aa77e122d4e661fa57b1e39 is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at Tenable (329906). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 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
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 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

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / CWE-119
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: 329906
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-64293

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.39/7.1.4/7.2-rc1
Patch: 04a177f91160ee18da98f5689482cf0f589ec869/0cdbb97a4dbd69abdd2ab998b4fbc7803d4b0b72/be93d186ae88a92e7aa77e122d4e661fa57b1e39

Timelineinfo

07/19/2026 CVE reserved
07/25/2026 +6 days Advisory disclosed
07/25/2026 +0 days VulDB entry created
07/27/2026 +1 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-64293 (🔒)
GCVE (CVE): GCVE-0-2026-64293
GCVE (VulDB): GCVE-100-383090

Entryinfo

Created: 07/25/2026 13:49
Updated: 07/27/2026 00:55
Changes: 07/25/2026 13:49 (60), 07/27/2026 00:55 (2)
Complete: 🔍
Cache ID: 216::103

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Discussion

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