Bug 1911309 (CVE-2020-35513) - CVE-2020-35513 kernel: Nfsd failure to clear umask after processing an open or create
Summary: CVE-2020-35513 kernel: Nfsd failure to clear umask after processing an open o...
Keywords:
Status: CLOSED ERRATA
Alias: CVE-2020-35513
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
low
low
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 1905208 1911634 1911635 1911636 1919911
Blocks: 1905197
TreeView+ depends on / blocked
 
Reported: 2020-12-28 17:22 UTC by Pedro Sampaio
Modified: 2021-02-23 16:16 UTC (History)
47 users (show)

Fixed In Version: kernel 4.17-rc1
Doc Type: If docs needed, set a value
Doc Text:
A flaw incorrect umask during file or directory modification in the Linux kernel NFS (network file system) functionality was found in the way user create and delete object using NFSv4.2 or newer if both simultaneously accessing the NFS by the other process that is not using new NFSv4.2. A user with access to the NFS could use this flaw to starve the resources causing denial of service.
Clone Of:
Environment:
Last Closed: 2021-02-02 14:42:12 UTC

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2021:0336 0 None None None 2021-02-02 12:00:45 UTC
Red Hat Product Errata RHSA-2021:0338 0 None None None 2021-02-02 12:02:26 UTC

Description Pedro Sampaio 2020-12-28 17:22:54 UTC 
A flaw was found in nfsd. A failure to clear umask after processing an open or create operation results in wrong permissions on a newly-created objects. 

References:

https://bugzilla.redhat.com/show_bug.cgi?id=1903303
Comment 8 Alex 2021-01-10 10:13:23 UTC 
Statement:

This flaw is rated as having Low impact because of the exploitation prerequisities and the fact that the attacker could only decrease the permissions of the file or directory.
Comment 13 Alex 2021-01-10 13:18:58 UTC 
Acknowledgments:

Name: J. Bruce Fields (fieldses.org)
Comment 14 Alex 2021-01-10 13:19:00 UTC 
External References:

https://patchwork.kernel.org/project/linux-nfs/patch/20180403203916.GH20297@fieldses.org/
Comment 15 Petr Matousek 2021-01-25 11:50:36 UTC 
Created kernel tracking bugs for this issue:

Affects: fedora-all [bug 1919911]
Comment 16 Justin M. Forbes 2021-01-25 17:36:27 UTC 
This was fixed for Fedora with the 4.15.18 stable kernel updates.
Comment 17 errata-xmlrpc 2021-02-02 12:00:40 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2021:0336 https://access.redhat.com/errata/RHSA-2021:0336
Comment 18 errata-xmlrpc 2021-02-02 12:02:20 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2021:0338 https://access.redhat.com/errata/RHSA-2021:0338
Comment 19 Product Security DevOps Team 2021-02-02 14:42:12 UTC 
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-35513
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