Linux Kernel up to 6.18.43/7.1.7/7.2-rc5 ksmbd smb2_handle_negotiate memory leak

CVSS Meta Temp Score
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CTI Interest Score
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9.5$0-$5k0.00+

Summaryinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 6.18.43/7.1.7/7.2-rc5. Affected by this issue is the function smb2_handle_negotiate of the component ksmbd. The manipulation results in memory leak. This vulnerability was named CVE-2026-74494. The attack may be performed from remote. There is no available exploit.

Detailsinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 6.18.43/7.1.7/7.2-rc5. Affected is the function smb2_handle_negotiate of the component ksmbd. The manipulation with an unknown input leads to a memory leak vulnerability. CWE is classifying the issue as CWE-401. The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: ksmbd: reject repeated SMB2 NEGOTIATE requests Unauthenticated client can send multiple successful SMB2 NEGOTIATE requests on one connection before SESSION_SETUP. While the connection is in KSMBD_SESS_NEED_SETUP, smb2_handle_negotiate() accepts another SMB3.1.1 NEGOTIATE and overwrites conn->preauth_info with a new allocation. Only the final allocation is freed when the connection is released, leaking one object for every additional successful request. A repeated SMB2 NEGOTIATE after a dialect has been selected is a protocol violation. MS-SMB2 section 3.3.5.4 requires the server to disconnect without replying in this case. Set the connection exiting when rejecting the request, in addition to suppressing the response. Reject SMB2 NEGOTIATE unless the connection is new or is waiting for the SMB2 NEGOTIATE that follows an SMB1 multi-protocol negotiate. Serialize both SMB1 and SMB2 negotiation paths under conn->srv_mutex, since they update connection-wide dialect and negotiation state. Move the locking contract to ksmbd_smb_negotiate_common(), where the state and dialect are selected, and add ksmbd_conn_new() for consistent state access.

The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2026-74494 since 08/15/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 08/15/2026). This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 6.18.44, 7.1.8 or 7.2-rc6 eliminates this vulnerability. Applying the patch a60b5da05e318d9a364dbac38c347c7f24e625e7/7e02cb30e8a1f5fc78cb10b220b06020e36d0bbe/cb469993b3a61a72653770856d37af616d72d05f is able to eliminate this problem.

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Productinfo

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Version

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 10.0
VulDB Meta Temp Score: 9.5

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Memory leak
CWE: CWE-401 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.18.44/7.1.8/7.2-rc6
Patch: a60b5da05e318d9a364dbac38c347c7f24e625e7/7e02cb30e8a1f5fc78cb10b220b06020e36d0bbe/cb469993b3a61a72653770856d37af616d72d05f

Timelineinfo

08/15/2026 Advisory disclosed
08/15/2026 +0 days CVE reserved
08/15/2026 +0 days VulDB entry created
08/15/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-74494 (🔒)
GCVE (CVE): GCVE-0-2026-74494
GCVE (VulDB): GCVE-100-390798

Entryinfo

Created: 08/15/2026 15:14
Changes: 08/15/2026 15:14 (59)
Complete: 🔍
Cache ID: 216::103

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