CVE-2021-26432: Windows Services for NFS ONCRPC XDR Driver Remote Code Execution Vulnerability

Overview

Severity: Critical (CVSS 9.8)
CVSS Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C
Category: Remote Code Execution
Exploit Status: Not Exploited
Exploitation Likelihood: More Likely
Patch Tuesday: 2021-Aug
Released: 2021-08-10
Last Updated: 2021-08-12
EPSS Score: 10.29% (percentile: 93.2%)

FAQ

What system configurations would expose this vulnerability? Servers that have installed the Network File System are exposed to this vulnerability in rpcxdr.sys. An attacker would require read or write permission to any file on an NFS share on the victim system. If NFS is configured to allow anonymous access, then the victim system would be vulnerable to unauthenticated attackers. Does this security update apply to non-server systems? Yes. While servers are much more likely to be exposed to this vulnerability, the security update to rpcxdr.sys applies to all Windows editions in the Security Updates table.

Affected Products (32)

Other

11568
11569
11570
11571
11572
11712
11713
11714
11896
11897
11898
11766
11767
11768
11769
11800
11801
11802
11803
10729
10735
10852
10853
10816
10855
10481
10482
10484
10378
10379
10483
10543

Security Updates (9)

Acknowledgments

Liubenjin from Codesafe Team of Legendsec at Qi'anxin Group

Revision History

2021-08-10: Information published.
2021-08-12: Added FAQ to provide further vulnerability details. This is an informational change only.