CVE-2024-1931

NLnet Labs Unbound version 1.18.0 up to and including version 1.19.1
contain a vulnerability that can cause denial of service by a certain code
path that can lead to an infinite loop. Unbound 1.18.0 introduced a feature
that removes EDE records from responses with size higher than the client’s
advertised buffer size. Before removing all the EDE records however, it
would try to see if trimming the extra text fields on those records would
result in an acceptable size while still retaining the EDE codes. Due to an
unchecked condition, the code that trims the text of the EDE records could
loop indefinitely. This happens when Unbound would reply with attached EDE
information on a positive reply and the client’s buffer size is smaller
than the needed space to include EDE records. The vulnerability can only be
triggered when the ‘ede: yes’ option is used; non default configuration.
From version 1.19.2 on, the code is fixed to avoid looping indefinitely.

Notes