Bug 1549861 (CVE-2017-18206)

Summary:	CVE-2017-18206 zsh: buffer overrun in symlinks
Product:	[Other] Security Response	Reporter:	Laura Pardo <lpardo>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
Version:	unspecified	CC:	dmaphy, james.antill, j, kdudka, rcosta, svashisht, yozone
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
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.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2018-11-30 00:34:24 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1567308, 1567309
Bug Blocks:	1549839

Description Laura Pardo 2018-02-27 22:30:29 UTC

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 22:39:45 UTC

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 14:06:30 UTC

(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 15:47:04 UTC

fixed in zsh-5.3.1-7.fc26

Comment 8 errata-xmlrpc 2018-06-19 04:56:19 UTC

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 07:30:05 UTC

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