Bug 1549861 – CVE-2017-18206 zsh: buffer overrun in symlinks

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Bug 1549861 - (CVE-2017-18206) CVE-2017-18206 zsh: buffer overrun in symlinks

Summary:	CVE-2017-18206 zsh: buffer overrun in symlinks

Status:	NEW

Aliases:	CVE-2017-18206

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

Priority	low Severity low
Target Milestone:	---
Target Release:	---
Assigned To:	Red Hat Product Security
QA Contact:
Docs Contact:

URL:
Whiteboard:	impact=low,public=20170509,reported=2...
Keywords:	Security

Depends On:	1567308 1567309
Blocks:	1549839
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Reported:	2018-02-27 17:30 EST by Laura Pardo
Modified:	2018-10-30 03:30 EDT (History)
CC List:	7 users (show)

See Also:
Fixed In Version:	zsh 5.4
Doc Type:	If docs needed, set a value
Doc Text:	A buffer overflow flaw was found in the zsh shell symbolic link resolver. A local, unprivileged user can create a specially crafted directory path which leads to a buffer overflow in the context of the user trying to do a symbolic link resolution in the aforementioned path. If the user affected is privileged, this leads to privilege escalation.
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RHEL 7.3 requirements from Atomic Host:
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External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2018:1932	None	None	None	2018-06-19 00:56 EDT
Red Hat Product Errata	RHSA-2018:3073	None	None	None	2018-10-30 03:30 EDT

Groups: None (edit)

Description Laura Pardo 2018-02-27 17:30:29 EST

A flaw was found in zsh prior 5.3.1. There was no check when copying to the internal xbuf2 for a preliminary test.


References:
https://sourceforge.net/p/zsh/code/ci/c7a9cf465dd620ef48d586026944d9bd7a0d5d6d

Comment 1 Jason Tibbitts 2018-02-27 17:39:45 EST

The oldest non EOL branch of Fedora, F26, has zsh 5.3.1.  However, it does not appear to have this patch, so I believe that zsh 5.3.1 is also vulnerable to this.

The current F27 version (5.4.2) does have this code and should not be vulnerable.

Comment 2 Kamil Dudka 2018-03-06 09:06:30 EST

(In reply to Laura Pardo from comment #0)
> A flaw was found in zsh prior 5.3.1.

The commit you refer to landed (192 commits) _after_ the 5.3.1 release.

Comment 3 Kamil Dudka 2018-03-06 10:47:04 EST

fixed in zsh-5.3.1-7.fc26

Comment 8 errata-xmlrpc 2018-06-19 00:56:19 EDT

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 6

Via RHSA-2018:1932 https://access.redhat.com/errata/RHSA-2018:1932

Comment 9 errata-xmlrpc 2018-10-30 03:30:05 EDT

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2018:3073 https://access.redhat.com/errata/RHSA-2018:3073

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