Bug 1921916 (CVE-2021-3326)

Summary:	CVE-2021-3326 glibc: Assertion failure in ISO-2022-JP-3 gconv module related to combining characters
Product:	[Other] Security Response	Reporter:	Pedro Sampaio <psampaio>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	arjun.is, ashankar, bdettelb, codonell, dj, fweimer, glibc-bugzilla, kaycoth, mfabian, mnewsome, pfrankli, sipoyare, tomckay
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	glibc 2.33	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in glibc's iconv() functionality. This flaw allows an attacker capable of supplying a crafted sequence of characters to an application using iconv() to convert from ISO-2022-JP-3 to cause an assertion failure. The highest threat from this vulnerability is to system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-05-18 14:38:12 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:	1925091, 1925093, 1921917, 1924919, 1924920, 1925088, 1925089, 1925090, 1925092, 1968676, 1968677, 1968678
Bug Blocks:	1921918

Description Pedro Sampaio 2021-01-28 20:47:06 UTC

The iconv function in the GNU C Library (aka glibc or libc6) 2.32 and earlier, when processing invalid input sequences in the ISO-2022-JP-3 encoding, fails an assertion in the code path and aborts the program, potentially resulting in a denial of service.

Upstream bug:

https://sourceware.org/bugzilla/show_bug.cgi?id=27256

Upstream patch:

https://sourceware.org/git/?p=glibc.git;a=commit;h=7d88c6142c6efc160c0ee5e4f85cde382c072888

Comment 1 Pedro Sampaio 2021-01-28 20:47:39 UTC

Created glibc tracking bugs for this issue:

Affects: fedora-all [bug 1921917]

Comment 4 Todd Cullum 2021-02-03 22:57:14 UTC

Flaw technical summary:

glibc's iconv() function, when converting from ISO-2022-JP-3 ( which would have a conversion descriptor allocated by a call to e.g. `iconv_open ("UTF-8", "ISO-2022-JP-3")` ), can trigger an assertion failure in the form:

`../iconv/skeleton.c:746: gconv: Assertion `outbuf == outerr' failed.`

when processing a specific character sequence. Thus, any application which relies upon glibc's inconv() function and which uses the aforementioned encodings, could be susceptible to a denial of service if it processes the sequence, potentially provided by an attacker.

Comment 7 Todd Cullum 2021-02-03 23:55:17 UTC

Mitigation:

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Comment 10 Todd Cullum 2021-02-11 19:48:01 UTC

Statement:

Exploitation of this flaw would cause the application to halt execution. It relies on processing untrusted input in the ISO-2022-JP-3 encoding or ISO-2022-JP-3 being used as a MIME charset in applications using iconv.

Comment 17 errata-xmlrpc 2021-05-18 13:26:26 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2021:1585 https://access.redhat.com/errata/RHSA-2021:1585

Comment 18 Product Security DevOps Team 2021-05-18 14:38:12 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-2021-3326