CVE-2021-47168
Description
A vulnerability was found in the NFS implementation in Linux Kernel causing memory corruption due to an incorrect size limit in filelayout_decode_layout(). Using "sizeof(struct nfs_fh)" instead of NFS_MAXFHSIZE led to buffer overflow by two bytes leads to potential memory corruption.
Statement
Red Hat has evaluated this vulnerability as having a Moderate severity because exploitation requires connecting to a malicious or compromised NFSv4.1 server that delivers a crafted pNFS layout structure. In typical Red Hat Enterprise Linux environments, storage shares are mounted exclusively from trusted internal servers, limiting exposure to unauthenticated remote attackers. Furthermore, while the improper size validation produces a small out-of-bounds memory write during layout decoding, the practical impact is constrained to a kernel crash and denial of service rather than arbitrary code execution.
Mitigation
Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.
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 | 5.5 | 9.8 |
| Attack Vector | Local | Local | Network |
| Attack Complexity | Low | Low | Low |
| Privileges Required | Low | Low | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | High |
| Integrity Impact | None | None | High |
| Availability Impact | High | High | High |
Vector
Red Hat: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: 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:H/A:H
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