avahi-daemon in Avahi through 0.6.32 and 0.7 inadvertently responds to IPv6 unicast queries with source addresses that are not on-link, which allows remote attackers to cause a denial of service (traffic amplification) and may cause information leakage by obtaining potentially sensitive information from the responding device via port-5353 UDP packets. NOTE: this may overlap CVE-2015-2809.

The originatesfromlocallegacyunicastsocket function in avahi-core/server.c in avahi-daemon 0.6.23 does not account for the network byte order of a port number when processing incoming multicast packets, which allows remote attackers to cause a denial of service (network bandwidth and CPU consumption) via a crafted legacy unicast mDNS query packet that triggers a multicast packet storm.

avahi-daemon-check-dns.sh in the Debian avahi package through 0.8-4 is executed as root via /etc/network/if-up.d/avahi-daemon and allows a local attacker to cause a denial of service or create arbitrary empty files via a symlink attack on files under /run/avahi-daemon. NOTE: this only affects the packaging for Debian GNU/Linux (used indirectly by SUSE) not the upstream Avahi product.

Avahi has a reachable assertion in lookupmulticastcallback

Avahi has a reachable assertion in lookupstart

Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. In versions 0.9rc2 and below, avahi-daemon can be crashed via a segmentation fault by sending an unsolicited mDNS response containing a recursive CNAME record, where the alias and canonical name point to the same domain (e.g., "h.local" as a CNAME for "h.local"). This causes unbounded recursion in the lookuphandlecname function, leading to stack exhaustion. The vulnerability affects record browsers where AVAHILOOKUPUSEMULTICAST is set explicitly, which includes record browsers created by resolvers used by nss-mdns. This issue is patched in commit 78eab31128479f06e30beb8c1cbf99dd921e2524.

A vulnerability was found in the avahi library. This flaw allows an unprivileged user to make a dbus call, causing the avahi daemon to crash.

A reachable assertion was found in avahidnspacketappendrecord.

References:

https://github.com/lathiat/avahi/issues/455

A reachable assertion was found in avahiescapelabel.

References:

https://github.com/lathiat/avahi/issues/454

A reachable assertion was found in avahialternativehostname.

References:

https://github.com/lathiat/avahi/issues/451

A reachable assertion was found in avahirdataparse.

References:

https://github.com/lathiat/avahi/issues/452

A reachable assertion was found in dbussethostname.

References:

https://github.com/lathiat/avahi/issues/453

Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. In versions up to and including 0.9-rc2, the simple protocol server ignores the documented client limit and accepts unlimited connections, allowing for easy local DoS. Although CLIENTSMAX is defined, serverwork() unconditionally accept()s and clientnew() always appends the new client and increments nclients. There is no check against the limit. When client cannot be accepted as a result of maximal socket number of avahi-daemon, it logs unconditionally error per each connection. Unprivileged local users can exhaust daemon memory and file descriptors, causing a denial of service system-wide for mDNS/DNS-SD. Exhausting local file descriptors causes increased system load caused by logging errors of each of request. Overloading prevents glibc calls using nss-mdns plugins to resolve .local. names and link-local addresses. As of time of publication, no known patched versions are available, but a candidate fix is available in pull request 808, and some workarounds are available. Simple clients are offered for nss-mdns package functionality. It is not possible to disable the unix socket /run/avahi-daemon/socket, but resolution requests received via DBus are not affected directly. Tools avahi-resolve, avahi-resolve-address and avahi-resolve-host-name are not affected, they use DBus interface. It is possible to change permissions of unix socket after avahi-daemon is started. But avahi-daemon does not provide any configuration for it. Additional access restrictions like SELinux can also prevent unwanted tools to access the socket and keep resolution working for trusted users.

Avahi has a reachable assertion in avahiwideareascancache

Avahi is a system which facilitates service discovery on a local network via the mDNS/DNS-SD protocol suite. Prior to version 0.9-rc4, any unprivileged local user can crash avahi-daemon by sending a single D-Bus method call with conflicting publish flags. This issue has been patched in version 0.9-rc4.

A flaw was found in avahi deamon. Denial of service can be triggered by writing long lines to /run/avahi-daemon/socket resulting in an unresponsive busy-loop of the daemon.

References:

https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=984938

A flaw was found in avahi 0.8-5. A reachable assertion is present in avahishostnameresolverstart function allowing a local attacker to crash the avahi service by requesting hostname resolutions through the avahi socket or dbus methods for invalid hostnames. The highest threat from this vulnerability is to the service availability.

A flaw was found in Avahi-daemon, which relies on fixed source ports for wide-area DNS queries. This issue simplifies attacks where malicious DNS responses are injected.

A flaw was found in the Avahi-daemon, where it initializes DNS transaction IDs randomly only once at startup, incrementing them sequentially after that. This predictable behavior facilitates DNS spoofing attacks, allowing attackers to guess transaction IDs.

The consumelabels function in avahi-core/dns.c in Avahi before 0.6.16 allows remote attackers to cause a denial of service (infinite loop) via a crafted compressed DNS response with a label that points to itself.

avahi-core/socket.c in avahi-daemon in Avahi before 0.6.29 allows remote attackers to cause a denial of service (infinite loop) via an empty mDNS (1) IPv4 or (2) IPv6 UDP packet to port 5353. NOTE: this vulnerability exists because of an incorrect fix for CVE-2010-2244.

Hugo Dias of the Synchron Security Labs discovered a remote denial of service flaw in the avahi daemon. A crafted multicast DNS (mDNS) packet with source port 0 can trigger assertion in originatesfromlocallegacyunicastsocket() function in avahi-core/server.c -- assert(port > 0); -- causing the daemon to call abort() and exit unexpectedly.

Scope of this attack is usually limited to a single LAN.

Ludwig Nussel reported: [1] http://www.openwall.com/lists/oss-security/2010/06/23/4

a deficiency in the way avahi daemon processed packets with corrupted checksum(s). A remote attacker on the same local are network (LAN) could send a DNS packet with broken checksum, that would cause avahi-daemon to exit unexpectedly due to a failed assertion check. Different vulnerability than CVE-2008-5081.

This vulnerability exposes Avahi-daemon to potential DNS spoofing attacks by using a fixed source port for queries. However, the impact is limited because it only affects wide-area DNS and can be mitigated by forwarding queries to local DNS resolvers (e.g., systemd-resolved), which provide better randomization. The impact is primarily on systems actively using wide-area DNS, with .local mDNS being unaffected.

The sequential increment of DNS transaction IDs makes Avahi vulnerable to DNS spoofing, allowing attackers to inject malicious DNS records. This can compromise the integrity of DNS responses, redirecting users to potentially harmful domains. This vulnerability poses a greater risk as it directly undermines the integrity of DNS resolution, affecting all systems using Avahi for wide-area DNS queries unless mitigations are applied.

It was discovered that the avahi deamon can be locally crashed by a dbus call made by an unprivileged user, causing a denial of service.

References:

https://github.com/lathiat/avahi/issues/375

Moderate: avahi security update

REJECT DO NOT USE THIS CANDIDATE NUMBER. ConsultIDs: CVE-2011-1002. Reason: This candidate is a reservation duplicate of CVE-2011-1002. Notes: All CVE users should reference CVE-2011-1002 instead of this candidate. All references and descriptions in this candidate have been removed to prevent accidental usage.

Ludwig Nussel reported: [1] http://www.openwall.com/lists/oss-security/2010/06/23/4

a deficiency in the way avahi daemon processed packets with corrupted checksum(s). A remote attacker on the same local are network (LAN) could send a DNS packet with broken checksum, that would cause avahi-daemon to exit unexpectedly due to a failed assertion check. Different vulnerability than CVE-2008-5081.

Hugo Dias of the Synchron Security Labs discovered a remote denial of service flaw in the avahi daemon. A crafted multicast DNS (mDNS) packet with source port 0 can trigger assertion in originatesfromlocallegacyunicastsocket() function in avahi-core/server.c -- assert(port > 0); -- causing the daemon to call abort() and exit unexpectedly.

Scope of this attack is usually limited to a single LAN.