Bug 1847244 (CVE-2020-8619)
| Summary: | CVE-2020-8619 bind: asterisk character in an empty non-terminal can cause an assertion failure in rbtdb.c | ||||||
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| Product: | [Other] Security Response | Reporter: | Huzaifa S. Sidhpurwala <huzaifas> | ||||
| Component: | vulnerability | Assignee: | Red Hat Product Security <security-response-team> | ||||
| Status: | CLOSED ERRATA | QA Contact: | |||||
| Severity: | medium | Docs Contact: | |||||
| Priority: | medium | ||||||
| Version: | unspecified | CC: | aegorenk, anon.amish, mruprich, msehnout, pemensik, psklenar, pzhukov, security-response-team, thozza, vonsch, zdohnal | ||||
| Target Milestone: | --- | Keywords: | Security | ||||
| Target Release: | --- | ||||||
| Hardware: | All | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | bind 9.11.20, bind 9.16.4 | Doc Type: | If docs needed, set a value | ||||
| Doc Text: |
A flaw was found in bind when an asterisk character is present in an empty non-terminal location within the DNS graph. This flaw could trigger an assertion failure, causing bind to crash. The highest threat from this vulnerability is to system availability.
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Story Points: | --- | ||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2020-11-04 02:25:57 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: | 1847246, 1848249 | ||||||
| Bug Blocks: | 1847243 | ||||||
| Attachments: |
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Acknowledgments: Name: ISC Mitigation:
As per upstream advisory: Unless a nameserver is providing authoritative service for one or more zones and at least one zone contains an empty non-terminal entry containing an asterisk ("*") character this defect cannot be encountered.
A would-be attacker who is allowed to change zone content could theoretically introduce such a record in order to exploit this condition to cause denial of service, though we consider the use of this vector unlikely because any such attack would require a significant privilege level and be easily traceable.
Created attachment 1697558 [details]
bind-9.11 patch
External References: https://kb.isc.org/docs/cve-2020-8619 Created bind tracking bugs for this issue: Affects: fedora-all [bug 1848249] Upstream bug: https://gitlab.isc.org/isc-projects/bind9/-/issues/1718 Upstream commit: https://gitlab.isc.org/isc-projects/bind9/-/commit/569cc155b8680d8ed12db1fabbe20947db24a0f9 Statement: Based on upstream affected versions, this flaw only affects the versions of bind shipped with Red Hat Enterprise Linux 8. This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2020:4500 https://access.redhat.com/errata/RHSA-2020:4500 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-2020-8619 |
As per upstream advisory: The asterisk character ("*") is allowed in DNS zone files, where it is most commonly present as a wildcard at a terminal node of the Domain Name System graph. However, the RFCs do not require and BIND does not enforce that an asterisk character be present only at a terminal node. A problem can occur when an asterisk is present in an empty non-terminal location within the DNS graph. If such a node exists, after a series of queries, named can reach an inconsistent state that results in the failure of an assertion check in rbtdb.c, followed by the program exiting due to the assertion failure.