Linux Kernel up to 6.1.177/6.6.144/6.12.96/6.18.39 nvmet-tcp nvmet_tcp_try_recv_ddgst use after free

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	4.21-

Summaryinfo

A vulnerability classified as very critical has been found in Linux Kernel up to 6.1.177/6.6.144/6.12.96/6.18.39. The affected element is the function nvmet_tcp_try_recv_ddgst of the component nvmet-tcp. This manipulation causes use after free. The identification of this vulnerability is CVE-2026-64535. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.1.177/6.6.144/6.12.96/6.18.39. It has been declared as very critical. Affected by this vulnerability is the function nvmet_tcp_try_recv_ddgst of the component nvmet-tcp. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: Fix potential UAF when ddgst mismatch Shivam Kumar found via vulnerability testing: When data digest is enabled on an NVMe/TCP connection and a digest mismatch occurs on a non-final H2C_DATA PDU during an R2T-based data transfer, the digest error handler in nvmet_tcp_try_recv_ddgst() calls nvmet_req_uninit() — which performs percpu_ref_put() on the submission queue — but does NOT mark the command as completed. It does not set cqe->status, does not modify rbytes_done, and does not clear any flag. When the subsequent fatal error triggers queue teardown, nvmet_tcp_uninit_data_in_cmds() iterates all commands, checks nvmet_tcp_need_data_in() for each one, and finds that the already-uninited command still appears to need data (because rbytes_done < transfer_len and cqe->status == 0). It therefore calls nvmet_req_uninit() a second time on the same command — a double percpu_ref_put against a single percpu_ref_get.

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-64535 since 07/19/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 07/27/2026).

The vulnerability scanner Nessus provides a plugin with the ID 330124 (Linux Distros Unpatched Vulnerability : CVE-2026-64535), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.1.178, 6.6.145, 6.12.97 or 6.18.40 eliminates this vulnerability. Applying the patch 96fe2513df590e74b04253a45089cae75569570e/e091ff83d962f9ed00d9bd70443676de9fe98bdc/6f9442983a3e4227afd1c83a5251ddbca585ea21/088ee46c18d99baef453afd74181dd40ade044ad/dbbd07d0a7020b80f6a7028e561908f7b83b3d5a is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at Tenable (330124). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.1.177
• 6.6.144
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
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• 6.12.95
• 6.12.96
• 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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• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39

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: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

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

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

Nessus ID: 330124
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-64535

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.1.178/6.6.145/6.12.97/6.18.40
Patch: 96fe2513df590e74b04253a45089cae75569570e/e091ff83d962f9ed00d9bd70443676de9fe98bdc/6f9442983a3e4227afd1c83a5251ddbca585ea21/088ee46c18d99baef453afd74181dd40ade044ad/dbbd07d0a7020b80f6a7028e561908f7b83b3d5a

Timelineinfo

07/19/2026 CVE reserved
07/27/2026 +8 days Advisory disclosed
07/27/2026 +0 days VulDB entry created
07/27/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-64535 (🔒)
GCVE (CVE): GCVE-0-2026-64535
GCVE (VulDB): GCVE-100-383389

Entryinfo

Created: 07/27/2026 09:55
Updated: 07/27/2026 21:49
Changes: 07/27/2026 09:55 (59), 07/27/2026 21:49 (2)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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