9.1
CRITICAL
CVSS 3.1
CVE-2026-68431
ksmbd: validate minimum PDU size for transform requests
Overview
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.
Details
INFO
Published Date :
Aug. 12, 2026, 12:17 a.m.
Last Modified :
Aug. 23, 2026, 1:16 p.m.
Remotely Exploit :
Yes !
Source :
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework
for assessing the severity of vulnerabilities in software and systems.
We collect and displays CVSS scores from various sources for each CVE.
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | CRITICAL | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
Solution
Patch the Linux kernel to validate minimum PDU size for transform requests.
- Update the Linux kernel.
- Ensure transform requests include headers.
- Validate ordinary SMB2 requests properly.
References
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-68431.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-68431 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-68431
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-68431 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-68431 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 23, 2026
Action Type Old Value New Value Added Reference https://git.kernel.org/stable/c/22f1aa35b87e471cc31b35b74451f46630863b12 Added Reference https://git.kernel.org/stable/c/32e486b70c256d5ef4baa5a2936ade2fea50e8eb Added Reference https://git.kernel.org/stable/c/928dda88d0e13fbca381255028f65b244343a4ea Added Reference https://git.kernel.org/stable/c/d8e5c5672724b8f3c4c099d2cf60239c996e5424 Added Reference https://git.kernel.org/stable/c/d9e9753dfd43bd27c956578df7804a3c90b80fdc Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'b62c510f59803f82f9b4c76ead2a56833b2984c7', 'versionType': 'git'}, {'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'cfc0b8e5080aec87700774e8568765eaa4b7b92b', 'versionType': 'git'}, {'status': 'affected', 'version': 'df3a4518aee64f21bcafa891105b468413f27431', 'versionType': 'git'}, {'status': 'affected', 'version': '543c12c2644e772caa6880662c2a852cfdc5a10c', 'versionType': 'git'}, {'status': 'affected', 'version': 'e9cb7be2fcbaee9e808b729e92948d38d52e5add', 'versionType': 'git'}, {'status': 'affected', 'version': '5.15.145', 'lessThan': '5.16', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.1.34', 'lessThan': '6.2', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.3.8', 'lessThan': '6.4', 'versionType': 'semver'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.4'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.4', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': 'df3a4518aee64f21bcafa891105b468413f27431', 'lessThan': '22f1aa35b87e471cc31b35b74451f46630863b12', 'versionType': 'git'}, {'status': 'affected', 'version': '543c12c2644e772caa6880662c2a852cfdc5a10c', 'lessThan': '928dda88d0e13fbca381255028f65b244343a4ea', 'versionType': 'git'}, {'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'd8e5c5672724b8f3c4c099d2cf60239c996e5424', 'versionType': 'git'}, {'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': '32e486b70c256d5ef4baa5a2936ade2fea50e8eb', 'versionType': 'git'}, {'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'd9e9753dfd43bd27c956578df7804a3c90b80fdc', 'versionType': 'git'}, {'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'b62c510f59803f82f9b4c76ead2a56833b2984c7', 'versionType': 'git'}, {'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'cfc0b8e5080aec87700774e8568765eaa4b7b92b', 'versionType': 'git'}, {'status': 'affected', 'version': 'e9cb7be2fcbaee9e808b729e92948d38d52e5add', 'versionType': 'git'}, {'status': 'affected', 'version': '5.15.145', 'lessThan': '5.15.217', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.1.34', 'lessThan': '6.1.184', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.3.8', 'lessThan': '6.4', 'versionType': 'semver'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.4'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.4', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '5.15.217', 'versionType': 'semver', 'lessThanOrEqual': '5.15.*'}, {'status': 'unaffected', 'version': '6.1.184', 'versionType': 'semver', 'lessThanOrEqual': '6.1.*'}, {'status': 'unaffected', 'version': '6.6.153', 'versionType': 'semver', 'lessThanOrEqual': '6.6.*'}, {'status': 'unaffected', 'version': '6.12.105', 'versionType': 'semver', 'lessThanOrEqual': '6.12.*'}, {'status': 'unaffected', 'version': '6.18.46', 'versionType': 'semver', 'lessThanOrEqual': '6.18.*'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'affected'}] -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 17, 2026
Action Type Old Value New Value Changed Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'b62c510f59803f82f9b4c76ead2a56833b2984c7', 'versionType': 'git'}, {'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'cfc0b8e5080aec87700774e8568765eaa4b7b92b', 'versionType': 'git'}, {'status': 'affected', 'version': 'df3a4518aee64f21bcafa891105b468413f27431', 'versionType': 'git'}, {'status': 'affected', 'version': '543c12c2644e772caa6880662c2a852cfdc5a10c', 'versionType': 'git'}, {'status': 'affected', 'version': 'e9cb7be2fcbaee9e808b729e92948d38d52e5add', 'versionType': 'git'}, {'status': 'affected', 'version': '5.15.145', 'lessThan': '5.16', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.1.34', 'lessThan': '6.2', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.3.8', 'lessThan': '6.4', 'versionType': 'semver'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.4'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.4', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc5', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'affected'}] [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'b62c510f59803f82f9b4c76ead2a56833b2984c7', 'versionType': 'git'}, {'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'cfc0b8e5080aec87700774e8568765eaa4b7b92b', 'versionType': 'git'}, {'status': 'affected', 'version': 'df3a4518aee64f21bcafa891105b468413f27431', 'versionType': 'git'}, {'status': 'affected', 'version': '543c12c2644e772caa6880662c2a852cfdc5a10c', 'versionType': 'git'}, {'status': 'affected', 'version': 'e9cb7be2fcbaee9e808b729e92948d38d52e5add', 'versionType': 'git'}, {'status': 'affected', 'version': '5.15.145', 'lessThan': '5.16', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.1.34', 'lessThan': '6.2', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.3.8', 'lessThan': '6.4', 'versionType': 'semver'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.4'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.4', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'affected'}] -
CVE Modified by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 13, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H -
New CVE Received by 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Aug. 12, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'b62c510f59803f82f9b4c76ead2a56833b2984c7', 'versionType': 'git'}, {'status': 'affected', 'version': '368ba06881c395f1c9a7ba22203cf8d78b4addc0', 'lessThan': 'cfc0b8e5080aec87700774e8568765eaa4b7b92b', 'versionType': 'git'}, {'status': 'affected', 'version': 'df3a4518aee64f21bcafa891105b468413f27431', 'versionType': 'git'}, {'status': 'affected', 'version': '543c12c2644e772caa6880662c2a852cfdc5a10c', 'versionType': 'git'}, {'status': 'affected', 'version': 'e9cb7be2fcbaee9e808b729e92948d38d52e5add', 'versionType': 'git'}, {'status': 'affected', 'version': '5.15.145', 'lessThan': '5.16', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.1.34', 'lessThan': '6.2', 'versionType': 'semver'}, {'status': 'affected', 'version': '6.3.8', 'lessThan': '6.4', 'versionType': 'semver'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'unaffected'}, {'repo': 'https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git', 'vendor': 'Linux', 'product': 'Linux', 'versions': [{'status': 'affected', 'version': '6.4'}, {'status': 'unaffected', 'version': '0', 'lessThan': '6.4', 'versionType': 'semver'}, {'status': 'unaffected', 'version': '7.1.6', 'versionType': 'semver', 'lessThanOrEqual': '7.1.*'}, {'status': 'unaffected', 'version': '7.2-rc5', 'versionType': 'original_commit_for_fix', 'lessThanOrEqual': '*'}], 'programFiles': ['fs/smb/server/connection.c'], 'defaultStatus': 'affected'}] Added 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. Added Reference https://git.kernel.org/stable/c/b62c510f59803f82f9b4c76ead2a56833b2984c7 Added Reference https://git.kernel.org/stable/c/cfc0b8e5080aec87700774e8568765eaa4b7b92b
EPSS is a daily estimate of the probability of exploitation activity
being observed over the next 30 days. Following chart shows the EPSS
score history of the vulnerability.