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Vulnerability · Published Jul 25, 2026 · Assigned by Linux

CVE-2026-64257smb: client: reject overlapping data areas in SMB2 responses

Critical 9.1

In plain English

A critical-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 0.7% (higher than 53% of all known vulnerabilities).

Severity (CVSS 3.1)9.1Critical
Exploit odds (30 days)0.7%top 46.6% 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: client: reject overlapping data areas in SMB2 responses Commit 53b7c271f06b ("smb: client: restrict implied bcc[0] exemption to responses without data area") restricted the implied bcc[0] length exception to responses without a data area. However, the overlap handling in __smb2_calc_size() clears data_length, which can make an invalid response appear to have no data area and so qualify for the exception. Track data area overlap separately and reject such responses before applying the length compatibility exceptions.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Ubuntu:22.04:LTSlinuxno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-allwinner-5.19no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-awsno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-aws-5.19no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-aws-6.14no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-aws-6.17no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-aws-6.2no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-aws-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-azureno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-azure-5.19no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-azure-6.11no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-azure-6.14no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-azure-6.2no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-azure-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-azure-fdeno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-azure-fde-5.19no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-azure-fde-6.14no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-azure-fde-6.2no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-azure-nvidia-6.14no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-gcpno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-gcp-5.19no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-gcp-6.11no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-gcp-6.14no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-gcp-6.2no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-gcp-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-gkeno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-gkeopno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-hwe-5.19no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-hwe-6.11no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-hwe-6.14no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-hwe-6.2no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-hwe-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-ibmno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-intel-iot-realtimeno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-intel-iotgno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-kvmno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-lowlatencyno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-lowlatency-hwe-5.19no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-lowlatency-hwe-6.11no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.2no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-lowlatency-hwe-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-nvidiano fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-nvidia-6.11no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-nvidia-6.2no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-nvidia-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-oem-5.17no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-oem-6.0no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-oem-6.1no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-oem-6.11no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-oem-6.14no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-oem-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-oem-6.8no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-oracleno fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-oracle-6.14no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-oracle-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-raspino fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-raspi-realtimeno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-realtimeno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-riscvno fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-riscv-5.19no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-riscv-6.14no fix listedUBUNTU-CVE-2026-64257
Ubuntu:24.04:LTSlinux-riscv-6.17no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-riscv-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-starfive-5.19no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-starfive-6.2no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-starfive-6.5no fix listedUBUNTU-CVE-2026-64257
Ubuntu:22.04:LTSlinux-xilinx-zynqmpno fix listedUBUNTU-CVE-2026-64257

Affected products (as reported)

VendorProductVersions
Linux Linux 31c6312608c60b72a1feb99a5afb680645a3e8a3 – before 445ece263131780dee273d727a4d6f11934feec7573e502d14714d2947e22e7eff40ec20a6a44a42 – before 36bfa52459e45c0d5b668de2f1c91f6dc5c67775419ec1b604d7fb60c10aec2dc062371f9fcd4940 – before 4a9d2657d3e05f6ed09c148cb127b4e58702275fceb875a375dedbf51c9425c1d13a2d7a8435c08c – before fdafa1e68dc75045b7b617e6e7d2854950804d836e9d10f62773b99bd927940fd9cbdfe7207e23ff – before 57cba95f0e97c6f6e45e6731da30aff091bd746053b7c271f06be4dd5cfc8c6ef552a8355c891a7f – before 8986c932905ea508d66da421eb2eb6e676ace1fe8d0bbc78046d264bbf6a574ea6f9072258a43e35b6a381c01e2ac98a48e32ac0f2a45bbadd9e26b0
Linux Linux see references

References