Linux Kernel up to 6.6.135/6.12.83/6.18.24/7.0.1 ksmbd_tcp_new_connection allocation of resources

CVSS Meta Temp Score
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CTI Interest Score
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7.2$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.6.135/6.12.83/6.18.24/7.0.1. It has been rated as critical. Affected by this vulnerability is the function ksmbd_tcp_new_connection. Performing a manipulation results in allocation of resources. This vulnerability is identified as CVE-2026-31711. The attack can be initiated remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.135/6.12.83/6.18.24/7.0.1. It has been classified as critical. This affects the function ksmbd_tcp_new_connection. The manipulation with an unknown input leads to a allocation of resources vulnerability. CWE is classifying the issue as CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: smb: server: fix active_num_conn leak on transport allocation failure Commit 77ffbcac4e56 ("smb: server: fix leak of active_num_conn in ksmbd_tcp_new_connection()") addressed the kthread_run() failure path. The earlier alloc_transport() == NULL path in the same function has the same leak, is reachable pre-authentication via any TCP connect to port 445, and was empirically reproduced on UML (ARCH=um, v7.0-rc7): a small number of forced allocation failures were sufficient to put ksmbd into a state where every subsequent connection attempt was rejected for the remainder of the boot. ksmbd_kthread_fn() increments active_num_conn before calling ksmbd_tcp_new_connection() and discards the return value, so when alloc_transport() returns NULL the socket is released and -ENOMEM returned without decrementing the counter. Each such failure permanently consumes one slot from the max_connections pool; once cumulative failures reach the cap, atomic_inc_return() hits the threshold on every subsequent accept and every new connection is rejected. The counter is only reset by module reload. An unauthenticated remote attacker can drive the server toward the memory pressure that makes alloc_transport() fail by holding open connections with large RFC1002 lengths up to MAX_STREAM_PROT_LEN (0x00FFFFFF); natural transient allocation failures on a loaded host produce the same drift more slowly. Mirror the existing rollback pattern in ksmbd_kthread_fn(): on the alloc_transport() failure path, decrement active_num_conn gated on server_conf.max_connections. Repro details: with the patch reverted, forced alloc_transport() NULL returns leaked counter slots and subsequent connection attempts -- including legitimate connects issued after the forced-fail window had closed -- were all rejected with "Limit the maximum number of connections". With this patch applied, the same connect sequence produces no rejections and the counter cycles cleanly between zero and one on every accept.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-31711 since 03/09/2026. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 07/05/2026). The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 325059 (Debian dla-4665 : affs-modules-6.1.0-48-4kc-malta-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.6.136, 6.12.84, 6.18.25, 7.0.2 or 7.1-rc1 eliminates this vulnerability. Applying the patch 97f8d2648ef4871e4cd335e2d769cb40054a6772/295a9fc6789d1011c36ded9f0f2907bb34fa0de4/283027aa93380380a0994f35dde3ec95318f2654/fb48185bcd946d42de7017cf27f912f8ab26acf0/6551300dc452ac16a855a83dbd1e74899542d3b3 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (325059) and CERT Bund (WID-SEC-2026-1346). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • Open Source Linux Kernel
  • RESF Rocky Linux
  • Microsoft Azure Linux
  • Red Hat OpenShift

Productinfo

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Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.4
VulDB Meta Temp Score: 7.2

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.5
CNA Vector (Linux): 🔒

CVSSv2info

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

Exploitinginfo

Class: Allocation of resources
CWE: CWE-770 / CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 325059
Nessus Name: Debian dla-4665 : affs-modules-6.1.0-48-4kc-malta-di - security update

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.136/6.12.84/6.18.25/7.0.2/7.1-rc1
Patch: 97f8d2648ef4871e4cd335e2d769cb40054a6772/295a9fc6789d1011c36ded9f0f2907bb34fa0de4/283027aa93380380a0994f35dde3ec95318f2654/fb48185bcd946d42de7017cf27f912f8ab26acf0/6551300dc452ac16a855a83dbd1e74899542d3b3

Timelineinfo

03/09/2026 CVE reserved
05/01/2026 +52 days Advisory disclosed
05/01/2026 +0 days VulDB entry created
07/05/2026 +65 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-31711 (🔒)
GCVE (CVE): GCVE-0-2026-31711
GCVE (VulDB): GCVE-100-360591
CERT Bund: WID-SEC-2026-1346 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 05/01/2026 16:47
Updated: 07/05/2026 20:06
Changes: 05/01/2026 16:47 (58), 05/05/2026 03:43 (7), 06/04/2026 05:24 (11), 06/09/2026 10:22 (1), 06/30/2026 21:11 (3), 07/05/2026 20:06 (2)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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