AUGUST 14, 2026
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Case File

CVE-2026-68431

CRITICAL · CVSS 9.1 EPSS 0.27%

Source: NVD + CISA KEV + EPSS · Published 2026-08-12 · Last synced 2026-08-14

CyberRota Analysis

AI-Generated

The vulnerability affects the Linux kernel's ksmbd component, specifically in how it validates the minimum PDU size for SMB2 transform requests. An attacker could exploit this flaw by sending a specially crafted short transform packet, potentially allowing them to read beyond the allocated memory and access sensitive data from an unauthenticated client. Organizations using Linux systems with SMB2.1 connections should prioritize addressing this issue to mitigate the risk of unauthorized data exposure.

CVE
CVE-2026-68431
Severity
CRITICAL
CVSS
9.1
EPSS
0.27%
Linux

Original NVD Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate minimum PDU size for transform requests The receive path applies the minimum SMB2 PDU size check only when ProtocolId is SMB2_PROTO_NUMBER. A packet carrying SMB2_TRANSFORM_PROTO_NUM bypasses the check even when the negotiated dialect does not provide transform handling. On an SMB 2.1 connection, a short transform packet therefore reaches init_smb2_rsp_hdr(), which interprets the request as a full SMB2 header and reads beyond the request allocation. The copied fields can then be returned to the unauthenticated client. Compression transforms are converted to ordinary SMB2 messages before protocol validation. After that conversion, validate ordinary SMB2 requests against SMB2_MIN_SUPPORTED_PDU_SIZE and require encryption transform requests to contain both a transform header and an SMB2 header. This rejects truncated requests before work allocation.