Bug 2024237 (CVE-2021-31566)

Summary:	CVE-2021-31566 libarchive: symbolic links incorrectly followed when changing modes, times, ACL and flags of a file while extracting an archive
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	bdettelb, caswilli, databases-maint, dkuc, fjansen, hhorak, jburrell, jwong, kaycoth, mike, ndevos, odubaj, panovotn, pkubat, praiskup, psegedy, sbiarozk, vkumar, vmugicag
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	libarchive 3.5.2	Doc Type:	If docs needed, set a value
Doc Text:	An improper link resolution flaw can occur while extracting an archive leading to changing modes, times, access control lists, and flags of a file outside of the archive. An attacker may provide a malicious archive to a victim user, who would trigger this flaw when trying to extract the archive. A local attacker may use this flaw to gain more privileges in a system.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2022-03-15 15:01:34 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:	2024238, 2024239, 2026075, 2026078, 2026828, 2026829, 2028035
Bug Blocks:	2024258

Description Guilherme de Almeida Suckevicz 2021-11-17 16:42:34 UTC

Some modes, times, ACLs and file flags especially on directories are set on archive_write_close() time. An archive can contain multiple entries with the same path. If a directory entry is marked for post-processing and a symlink entry with the same path "replaces" the directory with the symlink, the "fixup" postprocessing may alter the link target instead of the file itself.

Reference:
https://github.com/libarchive/libarchive/issues/1566

Upstream patch:
https://github.com/libarchive/libarchive/commit/b41daecb5ccb4c8e3b2c53fd6147109fc12c3043

Comment 1 Guilherme de Almeida Suckevicz 2021-11-17 16:42:59 UTC

Created libarchive tracking bugs for this issue:

Affects: fedora-all [bug 2024238]


Created mingw-libarchive tracking bugs for this issue:

Affects: fedora-all [bug 2024239]

Comment 4 Doran Moppert 2021-11-26 04:29:17 UTC

Second upstream patch completes the fix for this issue:

https://github.com/libarchive/libarchive/commit/e2ad1a2c3064fa9eba6274b3641c4c1beed25c0b

Comment 5 Doran Moppert 2021-11-26 04:30:37 UTC

*** Bug 2024242 has been marked as a duplicate of this bug. ***

Comment 11 Honza Horak 2021-12-22 13:35:58 UTC

There is another upstream fix that seems to be related (mentions the original b41daec):
https://github.com/libarchive/libarchive/commit/8a1bd5c18e896f0411a991240ce0d772bb02c840

which seems to be problematic and was later improved with this one:
https://github.com/libarchive/libarchive/commit/ede459d2ebb879f5eedb6f7abea203be0b334230

Comment 13 errata-xmlrpc 2022-03-15 10:20:03 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2022:0892 https://access.redhat.com/errata/RHSA-2022:0892

Comment 14 Product Security DevOps Team 2022-03-15 15:01:31 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-2021-31566