Bug 2407341 (CVE-2025-40099)

Summary: CVE-2025-40099 kernel: cifs: parse_dfs_referrals: prevent oob on malformed input
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedKeywords: Security
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's CIFS/SMB client implementation. In parse_dfs_referrals(), insufficient validation of server responses to FSCTL_DFS_GET_REFERRALS requests allows a malicious SMB server to send crafted replies that cause out-of-bounds memory access. Specifically, replies smaller than expected or with mismatched referral counts can trigger the vulnerability. A system connecting to a malicious or compromised SMB server could experience a kernel crash or memory corruption.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2025-10-30 10:02:36 UTC 
In the Linux kernel, the following vulnerability has been resolved:

cifs: parse_dfs_referrals: prevent oob on malformed input

Malicious SMB server can send invalid reply to FSCTL_DFS_GET_REFERRALS

- reply smaller than sizeof(struct get_dfs_referral_rsp)
- reply with number of referrals smaller than NumberOfReferrals in the
header

Processing of such replies will cause oob.

Return -EINVAL error on such replies to prevent oob-s.
Comment 1 Jon Moroney 2025-10-30 16:29:14 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2025103017-CVE-2025-40099-fdf0@gregkh/T