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Vulnerability · Published May 1, 2026 · Assigned by Linux

CVE-2026-31704ksmbd: use check_add_overflow() to prevent u16 DACL size overflow

Medium 5.5

In plain English

A medium-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 0.1% (higher than 2% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS NVD)5.5Medium
Exploit odds (30 days)0.1%top 98.3% 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: ksmbd: use check_add_overflow() to prevent u16 DACL size overflow set_posix_acl_entries_dacl() and set_ntacl_dacl() accumulate ACE sizes in u16 variables. When a file has many POSIX ACL entries, the accumulated size can wrap past 65535, causing the pointer arithmetic (char *)pndace + *size to land within already-written ACEs. Subsequent writes then overwrite earlier entries, and pndacl->size gets a truncated value. Use check_add_overflow() at each accumulation point to detect the wrap before it corrupts the buffer, consistent with existing check_mul_overflow() usage elsewhere in smbacl.c.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Debian:12linux6.1.176-1DEBIAN-CVE-2026-31704
Debian:13linux6.12.85-1DEBIAN-CVE-2026-31704
Debian:14linux7.0.3-1DEBIAN-CVE-2026-31704
Ubuntu:22.04:LTSlinuxno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux6.8.0-136.136UBUNTU-CVE-2026-31704
Ubuntu:25.10linuxno fix listedUBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux7.0.0-27.27UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-awsno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-aws6.8.0-1061.64UBUNTU-CVE-2026-31704
Ubuntu:25.10linux-awsno fix listedUBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-aws7.0.0-1008.8UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-aws-6.86.8.0-1061.64~22.04.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-azure6.8.0-1063.71UBUNTU-CVE-2026-31704
Ubuntu:25.10linux-azureno fix listedUBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-azure7.0.0-1010.10UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-azure-6.17no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-azure-6.86.8.0-1063.71~22.04.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-azure-fde6.8.0-1062.69UBUNTU-CVE-2026-31704
Ubuntu:25.10linux-azure-fdeno fix listedUBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-azure-fde7.0.0-1009.9UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-azure-fde-6.86.8.0-1062.69~22.04.1UBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-azure-nvidiano fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-gcpno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-gcp6.8.0-1064.72UBUNTU-CVE-2026-31704
Ubuntu:25.10linux-gcpno fix listedUBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-gcp7.0.0-1007.7UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-gcp-6.17no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-gcp-6.86.8.0-1064.72~22.04.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-gke6.8.0-1059.67UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-gkeopno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-gkeop6.8.0-1046.50UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-hwe-6.17no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-hwe-6.86.8.0-136.136~22.04.1UBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-hwe-7.07.0.0-28.28~24.04.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-ibmno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-ibm6.8.0-1061.62UBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-ibm7.0.0-1009.9UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-ibm-6.86.8.0-1061.62~22.04.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-intel-iotgno fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-kvmno fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-lowlatencyno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-lowlatency6.8.0-136.136.2UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.86.8.0-136.136.2~22.04.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-nvidia6.8.0-1059.62UBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-nvidia7.0.0-1013.13UBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-nvidia-6.17no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-nvidia-6.86.8.0-1059.62~22.04.1UBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-nvidia-lowlatency6.8.0-1059.62.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-nvidia-tegrano fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-nvidia-tegra6.8.0-1030.31UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-nvidia-tegra-igxno fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-oem-6.17no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-oracleno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-oracle6.8.0-1058.61UBUNTU-CVE-2026-31704
Ubuntu:25.10linux-oracleno fix listedUBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-oracle7.0.0-1007.7UBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-oracle-6.17no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-oracle-6.86.8.0-1058.61~22.04.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-raspi6.8.0-1061.65UBUNTU-CVE-2026-31704
Ubuntu:25.10linux-raspino fix listedUBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-raspi7.0.0-1014.14UBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-31704
Ubuntu:25.10linux-realtimeno fix listedUBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-realtime7.0.0-27.27.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-31704
Ubuntu:25.10linux-riscvno fix listedUBUNTU-CVE-2026-31704
Ubuntu:26.04:LTSlinux-riscv7.0.0-27.27.1UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-riscv-6.86.8.0-136.136~22.04.3UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-vmware6.8.0-1008.8UBUNTU-CVE-2026-31704
Ubuntu:24.04:LTSlinux-xilinx6.8.0-1033.34UBUNTU-CVE-2026-31704
Ubuntu:22.04:LTSlinux-xilinx-zynqmpno fix listedUBUNTU-CVE-2026-31704

Affected products (as reported)

VendorProductVersions
Linux Linux e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before 41e53a773db6342ac9a689ee5ba635c31744c9f0e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before 8d5729350b236896f51379588d9a690b7fafb8dbe2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before e1955a94b6f17f4b058afa955a6f187eb3ed7615e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before 5e7b8f3c539d69b2ed5f2408e2f75e68ce7eef43e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before ef7902be3f215b6bf7babe4dc9dd9a7d57dad7a7e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 – before 299f962c0b02d048fb45d248b4da493d03f3175d
Linux Linux 5.15

References