Bug 1953872 (CVE-2021-25216)

Summary:	CVE-2021-25216 bind: Vulnerability in BIND's GSSAPI security policy negotiation can be targeted by a buffer overflow attack
Product:	[Other] Security Response	Reporter:	Huzaifa S. Sidhpurwala <huzaifas>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED NOTABUG	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	aegorenk, anon.amish, dns-sig, mruprich, msehnout, pemensik, pzhukov, security-response-team, vonsch, zdohnal
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	bind 9.11.30, bind 9.16.14, bind 9.17.12	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in bind. The SPNEGO implementation used by BIND, which is a negotiation mechanism used by GSSAPI to support the secure exchange of keys used to verify the authenticity of communications between parties on a network, is subject to a buffer overflow attack. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-04-29 04:46:34 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:	1953880, 1953881, 1953882, 1953883, 1953884, 1953885, 1953886, 1953887, 1953888, 1953889, 1953890, 1953891, 1953892, 1954904
Bug Blocks:	1953850

Description Huzaifa S. Sidhpurwala 2021-04-27 06:15:36 UTC

As per upstream advisory:

GSS-TSIG is an extension to the TSIG protocol which is intended to support the secure exchange of keys for use in verifying the authenticity of communications between parties on a network.

SPNEGO is a negotiation mechanism used by GSSAPI, the application protocol interface for GSS-TSIG.

The SPNEGO implementation used by BIND has been found to be vulnerable to a buffer overflow attack.

Comment 1 Huzaifa S. Sidhpurwala 2021-04-27 06:15:39 UTC

Acknowledgments:

Name: ISC
Upstream: Trend Micro Zero Day Initiative

Comment 6 Huzaifa S. Sidhpurwala 2021-04-27 09:56:09 UTC

Statement:

Versions of bind package shipped with Red Hat Enterprise Linux do not enable ISC SPNEGO and therefore are not affected by this flaw.

Comment 7 Eric Christensen 2021-04-27 15:38:14 UTC

Mitigation:

This vulnerability only affects servers configured to use GSS-TSIG, most often to sign dynamic updates. If another mechanism can be used to authenticate updates, the vulnerability can be avoided  by choosing not to enable the use of GSS-TSIG features.

Comment 8 Huzaifa S. Sidhpurwala 2021-04-29 03:28:40 UTC

External References:

https://kb.isc.org/docs/cve-2021-25216

Comment 9 Huzaifa S. Sidhpurwala 2021-04-29 03:29:21 UTC

Created bind tracking bugs for this issue:

Affects: fedora-all [bug 1954904]

Comment 10 Product Security DevOps Team 2021-04-29 04:46:34 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-2021-25216