CVE-2025-40099
Description
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.
Statement
This vulnerability requires connecting to a malicious SMB server. While the attack vector is network-adjacent (requires SMB mount), exploitation depends on the attacker controlling the server. The impact is denial of service through kernel crash.
Mitigation
To mitigate this issue, prevent the cifs module from being loaded if SMB/CIFS filesystem access is not required. See https://access.redhat.com/solutions/41278 for instructions on how to blacklist a kernel module.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.5 | N/A | 9.4 |
| Attack Vector | Local | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | None | N/A | Low |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H
Understanding the Weakness (CWE)
Other
Technical Impact: Varies by Context
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