CVE-2026-68431: ksmbd: validate minimum PDU size for transform requests
- Is it exploited?
Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.
- How likely is exploitation in the next 30 days?
- 0.4%
EPSS score, percentile 30.4 of all scored records. A probability estimated by FIRST, not a report of exploitation.
- How severe?
- 9.1 Critical
CVSS v3.1 base score, given by the CNA
- What should I do?
CISA has set no required action, because the vulnerability is not in KEV.
The CVE record links no vendor advisory, patch or mitigation.
- Which versions are affected?
Affected
- from 5.15.145 to before 5.15.217
- from 6.1.34 to before 6.1.184
- from 6.3.8 to before 6.4
- 6.4
Unaffected before 6.4; 5.15.217; 6.1.184; 6.6.153; 6.12.105; 6.18.46; and 2 more
Source: CISA KEV 2026.10.29, as of ; FIRST EPSS, as of ; CVE List, as of . About the data.
What to do
Advisories and patches
The CVE record links no vendor advisory, patch or mitigation.
This summary is based on the CVE record as of . Check the vendor's advisory before you act: affected versions and fixes can change.
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | from df3a4518aee6 to before 22f1aa35b87e |
| Affected | from 543c12c2644e to before 928dda88d0e1 |
| Affected | from 368ba06881c3 to before d8e5c5672724 |
| Affected | from 368ba06881c3 to before 32e486b70c25 |
| Affected | from 368ba06881c3 to before d9e9753dfd43 |
| Affected | from 368ba06881c3 to before b62c510f5980 |
| Affected | from 368ba06881c3 to before cfc0b8e5080a |
| Affected | e9cb7be2fcba |
| Affected | from 5.15.145 to before 5.15.217 |
| Affected | from 6.1.34 to before 6.1.184 |
| Affected | from 6.3.8 to before 6.4 |
Versions not listed are: unaffected.
| Status | Versions |
|---|---|
| Affected | 6.4 |
| Unaffected | before 6.4 |
| Unaffected | 5.15.217 |
| Unaffected | 6.1.184 |
| Unaffected | 6.6.153 |
| Unaffected | 6.12.105 |
| Unaffected | 6.18.46 |
| Unaffected | 7.1.6 |
| Unaffected | 7.2 |
Versions not listed are: affected.
Versions the record lists as unaffected: 5.15.217, 6.1.184, 6.6.153, 6.12.105, 6.18.46, 7.1.6, 7.2.
Source: CVE List, as of . About the data.
About this vulnerability
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 transf…
Summary: CVE record, as of .
- CISA has not added CVE-2026-68431 to its Known Exploited Vulnerabilities (KEV) catalog, as of 29 Oct 2026.
- The CVE record was published on 12 Aug 2026.
- The CVE record carries a CVSS v3.1 base score of 9.1 (Critical), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 0.4% (percentile 30.4), as of 29 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
Source: CISA KEV 2026.10.29, as of ; CVE List, as of ; FIRST EPSS, as of . About the data.
Description
ksmbd: validate minimum PDU size for transform requests
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.
Source: CVE List, as of . About the data.
Timeline
| Date | Event |
|---|---|
| CVE record published | |
| CVE record last updated |
References
7
Known exploited Linux vulnerabilities
- CVE-2026-46300: Linux Kernel Missing Initialization of a Variable Vulnerability
- CVE-2025-39682: Linux Kernel Improper Check for Unusual or Exceptional Conditions Vulnerability
- CVE-2025-39964: Linux Kernel Race Condition Vulnerability
- CVE-2026-53266: Linux Kernel Out-of-Bounds Write Vulnerability
- CVE-2026-53362: Linux Kernel Unspecified Vulnerability