ISC : Security Vulnerabilities, CVEs, Published In 2019

With pipelining enabled each incoming query on a TCP connection requires a similar resource allocation to a query received via UDP or via TCP without pipelining enabled. A client using a TCP-pipelined connection to a server could consume more resources than the server has been provisioned to handle. When a TCP connection with a large number of pipelined queries is closed, the load on the server releasing these multiple resources can cause it to become unresponsive, even for queries that can be answered authoritatively or from cache. (This is most likely to be perceived as an intermittent server problem).

A defect in code added to support QNAME minimization can cause named to exit with an assertion failure if a forwarder returns a referral rather than resolving the query. This affects BIND versions 9.14.0 up to 9.14.6, and 9.15.0 up to 9.15.4.

Mirror zones are a BIND feature allowing recursive servers to pre-cache zone data provided by other servers. A mirror zone is similar to a zone of type secondary, except that its data is subject to DNSSEC validation before being used in answers, as if it had been looked up via traditional recursion, and when mirror zone data cannot be validated, BIND falls back to using traditional recursion instead of the mirror zone. However, an error in the validity checks for the incoming zone data can allow an on-path attacker to replace zone data that was validated with a configured trust anchor with forged data of the attacker's choosing. The mirror zone feature is most often used to serve a local copy of the root zone. If an attacker was able to insert themselves into the network path between a recursive server using a mirror zone and a root name server, this vulnerability could then be used to cause the recursive server to accept a copy of falsified root zone data. This affects BIND versions 9.14.0 up to 9.14.6, and 9.15.0 up to 9.15.4.

A missing check on incoming client requests can be exploited to cause a situation where the Kea server's lease storage contains leases which are rejected as invalid when the server tries to load leases from storage on restart. If the number of such leases exceeds a hard-coded limit in the Kea code, a server trying to restart will conclude that there is a problem with its lease store and give up. Versions affected: 1.4.0 to 1.5.0, 1.6.0-beta1, and 1.6.0-beta2

A packet containing a malformed DUID can cause the Kea DHCPv6 server process (kea-dhcp6) to exit due to an assertion failure. Versions affected: 1.4.0 to 1.5.0, 1.6.0-beta1, and 1.6.0-beta2.

A race condition which may occur when discarding malformed packets can result in BIND exiting due to a REQUIRE assertion failure in dispatch.c. Versions affected: BIND 9.11.0 -> 9.11.7, 9.12.0 -> 9.12.4-P1, 9.14.0 -> 9.14.2. Also all releases of the BIND 9.13 development branch and version 9.15.0 of the BIND 9.15 development branch and BIND Supported Preview Edition versions 9.11.3-S1 -> 9.11.7-S1.

There had existed in one of the ISC BIND libraries a bug in a function that was used by dhcpd when operating in DHCPv6 mode. There was also a bug in dhcpd relating to the use of this function per its documentation, but the bug in the library function prevented this from causing any harm. All releases of dhcpd from ISC contain copies of this, and other, BIND libraries in combinations that have been tested prior to release and are known to not present issues like this. Some third-party packagers of ISC software have modified the dhcpd source, BIND source, or version matchup in ways that create the crash potential. Based on reports available to ISC, the crash probability is large and no analysis has been done on how, or even if, the probability can be manipulated by an attacker. Affects: Builds of dhcpd versions prior to version 4.4.1 when using BIND versions 9.11.2 or later, or BIND versions with specific bug fixes backported to them. ISC does not have access to comprehensive version lists for all repackagings of dhcpd that are vulnerable. In particular, builds from other vendors may also be affected. Operators are advised to consult their vendor documentation.

An error in the EDNS Client Subnet (ECS) feature for recursive resolvers can cause BIND to exit with an assertion failure when processing a response that has malformed RRSIGs. Versions affected: BIND 9.10.5-S1 -> 9.11.6-S1 of BIND 9 Supported Preview Edition.

In BIND Supported Preview Edition, an error in the nxdomain-redirect feature can occur in versions which support EDNS Client Subnet (ECS) features. In those versions which have ECS support, enabling nxdomain-redirect is likely to lead to BIND exiting due to assertion failure. Versions affected: BIND Supported Preview Edition version 9.10.5-S1 -> 9.11.5-S5. ONLY BIND Supported Preview Edition releases are affected.

A programming error in the nxdomain-redirect feature can cause an assertion failure in query.c if the alternate namespace used by nxdomain-redirect is a descendant of a zone that is served locally. The most likely scenario where this might occur is if the server, in addition to performing NXDOMAIN redirection for recursive clients, is also serving a local copy of the root zone or using mirroring to provide the root zone, although other configurations are also possible. Versions affected: BIND 9.12.0-> 9.12.4, 9.14.0. Also affects all releases in the 9.13 development branch.

Controls for zone transfers may not be properly applied to Dynamically Loadable Zones (DLZs) if the zones are writable Versions affected: BIND 9.9.0 -> 9.10.8-P1, 9.11.0 -> 9.11.5-P2, 9.12.0 -> 9.12.3-P2, and versions 9.9.3-S1 -> 9.11.5-S3 of BIND 9 Supported Preview Edition. Versions 9.13.0 -> 9.13.6 of the 9.13 development branch are also affected. Versions prior to BIND 9.9.0 have not been evaluated for vulnerability to CVE-2019-6465.

"managed-keys" is a feature which allows a BIND resolver to automatically maintain the keys used by trust anchors which operators configure for use in DNSSEC validation. Due to an error in the managed-keys feature it is possible for a BIND server which uses managed-keys to exit due to an assertion failure if, during key rollover, a trust anchor's keys are replaced with keys which use an unsupported algorithm. Versions affected: BIND 9.9.0 -> 9.10.8-P1, 9.11.0 -> 9.11.5-P1, 9.12.0 -> 9.12.3-P1, and versions 9.9.3-S1 -> 9.11.5-S3 of BIND 9 Supported Preview Edition. Versions 9.13.0 -> 9.13.6 of the 9.13 development branch are also affected. Versions prior to BIND 9.9.0 have not been evaluated for vulnerability to CVE-2018-5745.

A failure to free memory can occur when processing messages having a specific combination of EDNS options. Versions affected are: BIND 9.10.7 -> 9.10.8-P1, 9.11.3 -> 9.11.5-P1, 9.12.0 -> 9.12.3-P1, and versions 9.10.7-S1 -> 9.11.5-S3 of BIND 9 Supported Preview Edition. Versions 9.13.0 -> 9.13.6 of the 9.13 development branch are also affected.

By design, BIND is intended to limit the number of TCP clients that can be connected at any given time. The number of allowed connections is a tunable parameter which, if unset, defaults to a conservative value for most servers. Unfortunately, the code which was intended to limit the number of simultaneous connections contained an error which could be exploited to grow the number of simultaneous connections beyond this limit. Versions affected: BIND 9.9.0 -> 9.10.8-P1, 9.11.0 -> 9.11.6, 9.12.0 -> 9.12.4, 9.14.0. BIND 9 Supported Preview Edition versions 9.9.3-S1 -> 9.11.5-S3, and 9.11.5-S5. Versions 9.13.0 -> 9.13.7 of the 9.13 development branch are also affected. Versions prior to BIND 9.9.0 have not been evaluated for vulnerability to CVE-2018-5743.

While backporting a feature for a newer branch of BIND9, RedHat introduced a path leading to an assertion failure in buffer.c:420. Affects RedHat versions bind-9.9.4-65.el7 -> bind-9.9.4-72.el7. No ISC releases are affected. Other packages from other distributions who made the same error may also be affected.

To provide fine-grained controls over the ability to use Dynamic DNS (DDNS) to update records in a zone, BIND 9 provides a feature called update-policy. Various rules can be configured to limit the types of updates that can be performed by a client, depending on the key used when sending the update request. Unfortunately, some rule types were not initially documented, and when documentation for them was added to the Administrator Reference Manual (ARM) in change #3112, the language that was added to the ARM at that time incorrectly described the behavior of two rule types, krb5-subdomain and ms-subdomain. This incorrect documentation could mislead operators into believing that policies they had configured were more restrictive than they actually were. This affects BIND versions prior to BIND 9.11.5 and BIND 9.12.3.

"deny-answer-aliases" is a little-used feature intended to help recursive server operators protect end users against DNS rebinding attacks, a potential method of circumventing the security model used by client browsers. However, a defect in this feature makes it easy, when the feature is in use, to experience an assertion failure in name.c. Affects BIND 9.7.0->9.8.8, 9.9.0->9.9.13, 9.10.0->9.10.8, 9.11.0->9.11.4, 9.12.0->9.12.2, 9.13.0->9.13.2.

An extension to hooks capabilities which debuted in Kea 1.4.0 introduced a memory leak for operators who are using certain hooks library facilities. In order to support multiple requests simultaneously, Kea 1.4 added a callout handle store but unfortunately the initial implementation of this store does not properly free memory in every case. Hooks which make use of query4 or query6 parameters in their callouts can leak memory, resulting in the eventual exhaustion of available memory and subsequent failure of the server process. Affects Kea DHCP 1.4.0.

Change #4777 (introduced in October 2017) introduced an unforeseen issue in releases which were issued after that date, affecting which clients are permitted to make recursive queries to a BIND nameserver. The intended (and documented) behavior is that if an operator has not specified a value for the "allow-recursion" setting, it SHOULD default to one of the following: none, if "recursion no;" is set in named.conf; a value inherited from the "allow-query-cache" or "allow-query" settings IF "recursion yes;" (the default for that setting) AND match lists are explicitly set for "allow-query-cache" or "allow-query" (see the BIND9 Administrative Reference Manual section 6.2 for more details); or the intended default of "allow-recursion {localhost; localnets;};" if "recursion yes;" is in effect and no values are explicitly set for "allow-query-cache" or "allow-query". However, because of the regression introduced by change #4777, it is possible when "recursion yes;" is in effect and no match list values are provided for "allow-query-cache" or "allow-query" for the setting of "allow-recursion" to inherit a setting of all hosts from the "allow-query" setting default, improperly permitting recursion to all clients. Affects BIND 9.9.12, 9.10.7, 9.11.3, 9.12.0->9.12.1-P2, the development release 9.13.0, and also releases 9.9.12-S1, 9.10.7-S1, 9.11.3-S1, and 9.11.3-S2 from BIND 9 Supported Preview Edition.

A problem with the implementation of the new serve-stale feature in BIND 9.12 can lead to an assertion failure in rbtdb.c, even when stale-answer-enable is off. Additionally, problematic interaction between the serve-stale feature and NSEC aggressive negative caching can in some cases cause undesirable behavior from named, such as a recursion loop or excessive logging. Deliberate exploitation of this condition could cause operational problems depending on the particular manifestation -- either degradation or denial of service. Affects BIND 9.12.0 and 9.12.1.

An error in zone database reference counting can lead to an assertion failure if a server which is running an affected version of BIND attempts several transfers of a slave zone in quick succession. This defect could be deliberately exercised by an attacker who is permitted to cause a vulnerable server to initiate zone transfers (for example: by sending valid NOTIFY messages), causing the named process to exit after failing the assertion test. Affects BIND 9.12.0 and 9.12.1.

While handling a particular type of malformed packet BIND erroneously selects a SERVFAIL rcode instead of a FORMERR rcode. If the receiving view has the SERVFAIL cache feature enabled, this can trigger an assertion failure in badcache.c when the request doesn't contain all of the expected information. Affects BIND 9.10.5-S1 to 9.10.5-S4, 9.10.6-S1, 9.10.6-S2.

A malicious client which is allowed to send very large amounts of traffic (billions of packets) to a DHCP server can eventually overflow a 32-bit reference counter, potentially causing dhcpd to crash. Affects ISC DHCP 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0.

Failure to properly bounds-check a buffer used for processing DHCP options allows a malicious server (or an entity masquerading as a server) to cause a buffer overflow (and resulting crash) in dhclient by sending a response containing a specially constructed options section. Affects ISC DHCP versions 4.1.0 -> 4.1-ESV-R15, 4.2.0 -> 4.2.8, 4.3.0 -> 4.3.6, 4.4.0

BIND was improperly sequencing cleanup operations on upstream recursion fetch contexts, leading in some cases to a use-after-free error that can trigger an assertion failure and crash in named. Affects BIND 9.0.0 to 9.8.x, 9.9.0 to 9.9.11, 9.10.0 to 9.10.6, 9.11.0 to 9.11.2, 9.9.3-S1 to 9.9.11-S1, 9.10.5-S1 to 9.10.6-S1, 9.12.0a1 to 9.12.0rc1.