Bug 1545017 – CVE-2018-6954 systemd: Mishandled symlinks in systemd-tmpfiles allows local users to obtain ownership of arbitrary files

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Bug 1545017 - (CVE-2018-6954) CVE-2018-6954 systemd: Mishandled symlinks in systemd-tmpfiles allows local users to obtain ownership of arbitrary files

Summary:	CVE-2018-6954 systemd: Mishandled symlinks in systemd-tmpfiles allows local u...

Status:	NEW

Aliases:	CVE-2018-6954

Product:	Security Response
Classification:	Other
Component:	vulnerability (Show other bugs)
Sub Component:
Version:	unspecified
Hardware:	All Linux

Priority	medium Severity medium
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Assigned To:	Red Hat Product Security
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URL:
Whiteboard:	impact=moderate,public=20180125,repor...
Keywords:	Security

Depends On:	1545018 1573211 1545019
Blocks:	1552047
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Reported:	2018-02-13 23:31 EST by Sam Fowler
Modified:	2018-07-03 04:05 EDT (History)
CC List:	7 users (show)

See Also:
Fixed In Version:
Doc Type:	If docs needed, set a value
Doc Text:	It has been discovered that systemd-tmpfiles mishandles symbolic links present in non-terminal path components. In some configurations a local user could use this vulnerability to get access to arbitrary files when the systemd-tmpfiles command is run.
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Description Sam Fowler 2018-02-13 23:31:46 EST

systemd-tmpfiles in systemd through version 237 mishandles symlinks present in non-terminal path components, allowing local users to obtain ownership of arbitrary files under certain configurations.

Depending on the configuration and access to files in /etc/tmpfiles.d, a local user can potentially create a symlink allowing them obtain full access to arbitrary files when the systemd-tmpfiles command is run. 

This occurs even if the fs.protected_symlinks sysctl is turned on.


Upstream Issue:

https://github.com/systemd/systemd/issues/7986

Comment 1 Sam Fowler 2018-02-13 23:32:13 EST

Created systemd tracking bugs for this issue:

Affects: fedora-all [bug 1545018]

Comment 6 Riccardo Schirone 2018-05-02 04:30:57 EDT

Patches:
https://github.com/systemd/systemd/pull/8358
https://github.com/systemd/systemd/pull/8822

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