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 lookup_handle_cname function, leading to stack exhaustion. The vulnerability affects record browsers where AVAHI_LOOKUP_USE_MULTICAST is set explicitly, which includes record browsers created by resolvers used by nss-mdns. This issue is patched in commit 78eab31128479f06e30beb8c1cbf99dd921e2524.
Weakness
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Avahi | Avahi | * | 0.9 (excluding) |
| Avahi | Avahi | 0.9-rc1 (including) | 0.9-rc1 (including) |
| Avahi | Avahi | 0.9-rc2 (including) | 0.9-rc2 (including) |