CVE-2026-64257: smb: client: reject overlapping data areas in SMB2 responses
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 smb2calcsize() clears datalength, 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 Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade to a fixed release to a version that resolves this vulnerability.
Patch 53b7c271f06b
Event History
Frequently Asked Questions
What is the severity of CVE-2026-64257?
The severity of CVE-2026-64257 is rated as critical with a CVSS score of 9.1.
How do I fix CVE-2026-64257?
To fix CVE-2026-64257, users should update their Linux kernel to the latest version where the vulnerability has been resolved.
What type of systems are affected by CVE-2026-64257?
CVE-2026-64257 affects systems running the Linux kernel that utilize SMB2 for file sharing.
What impact does CVE-2026-64257 have on affected systems?
CVE-2026-64257 can potentially allow for data integrity issues due to overlapping data areas in SMB2 responses.
When was CVE-2026-64257 published?
CVE-2026-64257 was published on July 25, 2026.