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Vulnerability · Published Dec 6, 2025 · Assigned by Linux

CVE-2025-40285smb/server: fix possible refcount leak in smb2_sess_setup()

High 7.5

In plain English

A high-severity security flaw in Linux from Linux. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 38% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.4%top 61.5% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

In the Linux kernel, the following vulnerability has been resolved: smb/server: fix possible refcount leak in smb2_sess_setup() Reference count of ksmbd_session will leak when session need reconnect. Fix this by adding the missing ksmbd_user_session_put().

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.159-1DEBIAN-CVE-2025-40285
Debian:13linux6.12.63-1DEBIAN-CVE-2025-40285
Debian:14linux6.17.9-1DEBIAN-CVE-2025-40285
Ubuntu:22.04:LTSlinuxno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux6.8.0-106.106UBUNTU-CVE-2025-40285
Ubuntu:25.10linux6.17.0-14.14UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-awsno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-aws6.8.0-1050.53UBUNTU-CVE-2025-40285
Ubuntu:25.10linux-aws6.17.0-1007.7UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-aws-6.176.17.0-1007.7~24.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-aws-6.86.8.0-1050.53~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-azureno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-azure6.8.0-1051.57UBUNTU-CVE-2025-40285
Ubuntu:25.10linux-azure6.17.0-1008.8UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-azure-6.86.8.0-1051.57~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1058.65UBUNTU-CVE-2025-40285
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-azure-fde-6.86.8.0-1058.65~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-gcpno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-gcp6.8.0-1052.55UBUNTU-CVE-2025-40285
Ubuntu:25.10linux-gcp6.17.0-1007.7UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-gcp-6.176.17.0-1008.8~24.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-gcp-6.86.8.0-1052.55~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-gke6.8.0-1048.53UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-gkeopno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1035.38UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-hwe-6.86.8.0-106.106~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-ibmno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-ibm6.8.0-1049.49UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-ibm-6.86.8.0-1049.49~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-intel-iotgno fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-kvmno fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-lowlatencyno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-106.106.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.86.8.0-106.106.1~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-nvidia6.8.0-1049.52UBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-nvidia-6.176.17.0-1008.8UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-nvidia-6.86.8.0-1049.52~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-nvidia-lowlatency6.8.0-1049.52.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-nvidia-tegrano fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1020.20UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-nvidia-tegra-igxno fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-oem-6.176.17.0-1011.11UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-oracleno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-oracle6.8.0-1047.48UBUNTU-CVE-2025-40285
Ubuntu:25.10linux-oracle6.17.0-1007.7UBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-oracle-6.176.17.0-1007.7~24.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-oracle-6.86.8.0-1047.48~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-raspi6.8.0-1050.54UBUNTU-CVE-2025-40285
Ubuntu:25.10linux-raspi6.17.0-1008.8UBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2025-40285
Ubuntu:25.10linux-realtime6.17.0-1006.7UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2025-40285
Ubuntu:25.10linux-riscv6.17.0-14.14.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-riscv-6.86.8.0-106.106~22.04.1UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2025-40285
Ubuntu:24.04:LTSlinux-xilinx6.8.0-1028.29UBUNTU-CVE-2025-40285
Ubuntu:22.04:LTSlinux-xilinx-zynqmpno fix listedUBUNTU-CVE-2025-40285

Affected products (as reported)

VendorProductVersions
Linux Linux 37a0e2b362b3150317fb6e2139de67b1e29ae5ff – before 6fc935f798d44a8eb8a5e6659198399fbf57b981450a844c045ff0895d41b05a1cbe8febd1acfcfd – before e671f9bb97805771380c98de944e2ceab6949188a39e31e22a535d47b14656a7d6a893c7f6cf758c – before dcc51dfe6ff26b52cac106865a172ac982d78401b95629435b84b9ecc0c765995204a4d8a913ed52 – before d37b2c81c83d6c0d5ca582f4fe73c672983f9e0db95629435b84b9ecc0c765995204a4d8a913ed52 – before 379510a815cb2e64eb0a379cb62295d6ade65df02107ab40629aeabbec369cf34b8cf0f288c3eb1b6.1.121 – before 6.1.1596.6.67 – before 6.6.117
Linux Linux 6.13

References