CVE-2024-8508

NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with very large RRsets that it needs to perform name compression for. Malicious upstreams responses with very large RRsets can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. The vulnerability can be exploited by a malicious actor querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. Unbound version 1.21.1 introduces a hard limit on the number of name compression calculations it is willing to do per packet. Packets that need more compression will result in semi-compressed packets or truncated packets, even on TCP for huge messages, to avoid locking the CPU for long. This change should not affect normal DNS traffic.

NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with very large RRsets that it needs to perform name compression for. Malicious upstreams responses with very large RRsets can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. The vulnerability can be exploited by a malicious actor querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. Unbound version 1.21.1 introduces a hard limit on the number of name compression calculations it is willing to do per packet. Packets that need more compression will result in semi-compressed packets or truncated packets, even on TCP for huge messages, to avoid locking the CPU for long. This change should not affect normal DNS traffic.

NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with very large RRsets that it needs to perform name compression for. Malicious upstreams responses with very large RRsets can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. The vulnerability can be exploited by a malicious actor querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. Unbound version 1.21.1 introduces a hard limit on the number of name compression calculations it is willing to do per packet. Packets that need more compression will result in semi-compressed packets or truncated packets, even on TCP for huge messages, to avoid locking the CPU for long. This change should not affect normal DNS traffic.

Unbound is a validating, recursive, caching DNS resolver. It is designed to be fast and lean and incorporates modern features based on open standards. To help increase online privacy, Unbound supports DNS-over-TLS which allows clients to encrypt their communication. Unbound is available for most platforms such as FreeBSD, OpenBSD, NetBSD, MacOS, Linux and Microsoft Windows. Unbound is a totally free, open source software under the BSD license. It doesn't make custom builds or provide specific features to paying customers only.

Security Fix(es):

NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with very large RRsets that it needs to perform name compression for. Malicious upstreams responses with very large RRsets can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. The vulnerability can be exploited by a malicious actor querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. Unbound version 1.21.1 introduces a hard limit on the number of name compression calculations it is willing to do per packet. Packets that need more compression will result in semi-compressed packets or truncated packets, even on TCP for huge messages, to avoid locking the CPU for long. This change should not affect normal DNS traffic.(CVE-2024-8508)

The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

Security Fix(es):

• unbound: Unbounded name compression could lead to Denial of Service (CVE-2024-8508)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

Security Fix(es):

• unbound: Unbounded name compression could lead to Denial of Service (CVE-2024-8508)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with very large RRsets that it needs to perform name compression for. Malicious upstreams responses with very large RRsets can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. The vulnerability can be exploited by a malicious actor querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. Unbound version 1.21.1 introduces a hard limit on the number of name compression calculations it is willing to do per packet. Packets that need more compression will result in semi-compressed packets or truncated packets, even on TCP for huge messages, to avoid locking the CPU for long. This change should not affect normal DNS traffic.

The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

Security Fix(es):

• unbound: Unbounded name compression could lead to Denial of Service (CVE-2024-8508)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

Security Fix(es):

• unbound: unrestricted reconfiguration enabled to anyone that may lead to local privilege escalation (CVE-2024-1488)
• unbound: Unbounded name compression could lead to Denial of Service (CVE-2024-8508)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

Security Fix(es):

• unbound: Unbounded name compression could lead to Denial of Service (CVE-2024-8508)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

• CVE-2024-8508: Limit number of name compression calculations per packet to prevent CPU lock and potential denial of service

• CVE-2024-8508: limit number of name compression calculations per packet to prevent denial of service attacks.

• CVE-2024-8508: limit number of name compression calculations per packet to prevent denial of service attacks.

• CVE-2024-8508: limit number of name compression calculations per packet to prevent denial of service attacks.

• CVE-2024-8508: limit number of name compression calculations per packet to prevent CPU locking and potential denial of service

NLnet Labs Unbound up to and including version 1.21.0 contains a vulnerability when handling replies with very large RRsets that it needs to perform name compression for. Malicious upstreams responses with very large RRsets can cause Unbound to spend a considerable time applying name compression to downstream replies. This can lead to degraded performance and eventually denial of service in well orchestrated attacks. The vulnerability can be exploited by a malicious actor querying Unbound for the specially crafted contents of a malicious zone with very large RRsets. Before Unbound replies to the query it will try to apply name compression which was an unbounded operation that could lock the CPU until the whole packet was complete. Unbound version 1.21.1 introduces a hard limit on the number of name compression calculations it is willing to do per packet. Packets that need more compression will result in semi-compressed packets or truncated packets, even on TCP for huge messages, to avoid locking the CPU for long. This change should not affect normal DNS traffic.

These are all security issues fixed in the libunbound8-1.21.1-1.1 package on the GA media of openSUSE Tumbleweed.

The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

Security Fix(es):

• unbound: Unbounded name compression could lead to Denial of Service (CVE-2024-8508)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

The unbound packages provide a validating, recursive, and caching DNS or DNSSEC resolver.

Security Fix(es):

• unbound: unrestricted reconfiguration enabled to anyone that may lead to local privilege escalation (CVE-2024-1488)

• unbound: Unbounded name compression could lead to Denial of Service (CVE-2024-8508)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

This update for unbound fixes the following issues:

• CVE-2024-8508: Fixed unbounded name compression that could lead to denial of service (bsc#1231284)

This update for unbound fixes the following issues:

• CVE-2024-8508: Fixed unbounded name compression that could lead to denial of service (bsc#1231284)

This update for unbound fixes the following issues:

• Update to 1.22.0: Features:

  • Add iter-scrub-ns, iter-scrub-cname and max-global-quota configuration options.
  • Merge patch to fix for glue that is outside of zone, with harden-unverified-glue, from Karthik Umashankar (Microsoft). Enabling this option protects the Unbound resolver against bad glue, that is unverified out of zone glue, by resolving them. It uses the records as last resort if there is no other working glue.
  • Add redis-command-timeout: 20 and redis-connect-timeout: 200, that can set the timeout separately for commands and the connection set up to the redis server. If they are not specified, the redis-timeout value is used.
  • Log timestamps in ISO8601 format with timezone. This adds the option log-time-iso: yes that logs in ISO8601 format.
  • DNS over QUIC. This adds quic-port: 853 and quic-size: 8m that enable dnsoverquic, and the counters num.query.quic and mem.quic in the statistics output. The feature needs to be enabled by compiling with libngtcp2, with --with-libngtcp2=path and libngtcp2 needs openssl+quic, pass that with --with-ssl=path to compile unbound as well.

  Bug Fixes:

  • unbound-control-setup hangs while testing for openssl presence starting from version 1.21.0.
  • Fix error: "memory exhausted" when defining more than 9994 local-zones.
  • Fix documentation for cache_fill_missing function.
  • Fix Loads of logs: "validation failure: key for validation <domain>. is marked as invalid because of a previous" for non-DNSSEC signed zone.
  • Fix that when rpz is applied the message does not get picked up by the validator. That stops validation failures for the message.
  • Fix that stub-zone and forward-zone clauses do not exhaust memory for long content.
  • Fix to print port number in logs for auth zone transfer activities.
  • b.root renumbering.
  • Add new IANA trust anchor.
  • Fix config file read for dnstap-sample-rate.
  • Fix alloc-size and calloc-transposed-args compiler warnings.
  • Fix to limit NSEC and NSEC3 TTL when aggressive nsec is enabled (RFC9077).
  • Fix dns64 with prefetch that the prefetch is stored in cache.
  • Attempt to further fix doh_downstream_buffer_size.tdir flakiness.
  • More clear text for prefetch and minimal-responses in the unbound.conf man page.
  • Fix cache update when serve expired is used. Expired records are favored over resolution and validation failures when serve-expired is used.
  • Fix negative cache NSEC3 parameter compares for zero length NSEC3 salt.
  • Fix unbound-control-setup hangs sometimes depending on the openssl version.
  • Fix Cannot override tcp-upstream and tls-upstream with forward-tcp-upstream and forward-tls-upstream.
  • Fix to limit NSEC TTL for messages from cachedb. Fix to limit the prefetch ttl for messages after a CNAME with short TTL.
  • Fix to disable detection of quic configured ports when quic is not compiled in.
  • Fix harden-unverified-glue for AAAA cache_fill_missing lookups.
  • Fix contrib/aaaa-filter-iterator for change in call signature for cache_fill_missing.
  • Fix to display warning if quic-port is set but dnsoverquic is not enabled when compiled.
  • Fix dnsoverquic to extend the number of streams when one is closed.
  • Fix for dnstap with dnscrypt and dnstap without dnsoverquic.
  • Fix for dnsoverquic and dnstap to use the correct dnstap environment.

• Update to 1.21.1: Security Fixes:

  • CVE-2024-8508: unbounded name compression could lead to denial of service. (bsc#1231284)

This update for unbound fixes the following issues:

Update to 1.22.0:

• CVE-2024-8508: Fixed unbounded name compression that could have led to a denial of service (bsc#1231284).

Toshifumi Sakaguchi discovered that Unbound incorrectly handled name compression for large RRsets, which could lead to excessive CPU usage. An attacker could potentially use this issue to cause a denial of service by sending specially crafted DNS responses.