CVE-2026-23220: ksmbd: fix infinite loop caused by next_smb2_rcv_hdr_off reset in error paths
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix infinite loop caused by nextsmb2rcvhdroff reset in error paths
The problem occurs when a signed request fails smb2 signature verification check. In processrequest(), if checksignreq() returns an error, setsmb2rspstatus(work, STATUSACCESSDENIED) is called. setsmb2rspstatus() set work->nextsmb2rcvhdroff as zero. By resetting nextsmb2rcvhdroff to zero, the pointer to the next command in the chain is lost. Consequently, ischainedsmb2message() continues to point to the same request header instead of advancing. If the header's NextCommand field is non-zero, the function returns true, causing handleksmbdwork() to repeatedly process the same failed request in an infinite loop. This results in the kernel log being flooded with "bad smb2 signature" messages and high CPU usage.
This patch fixes the issue by changing the return value from SERVERHANDLERCONTINUE to SERVERHANDLERABORT. This ensures that the processing loop terminates immediately rather than attempting to continue from an invalidated offset.
Affected Software
Remediation
Event History
Frequently Asked Questions
What is the severity of CVE-2026-23220?
CVE-2026-23220 has been classified as a medium severity vulnerability.
How do I fix CVE-2026-23220?
To fix CVE-2026-23220, you should update to the latest stable version of the Linux kernel that includes the security patch.
What systems are affected by CVE-2026-23220?
CVE-2026-23220 affects systems running the Linux kernel with ksmbd configurations.
What is the impact of CVE-2026-23220?
The impact of CVE-2026-23220 is the potential for an infinite loop when handling failed smb2 signature verifications.
When was CVE-2026-23220 reported?
CVE-2026-23220 was reported as a vulnerability in the Linux kernel related to the ksmbd component.