Resource management error in Unbound - CVE-2024-33655
Published: May 12, 2024
Vulnerability identifier: #VU89361
CSH Severity: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2024-33655
CWE-ID: CWE-399
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
Unbound
Unbound
Software vendor:
NLnet Labs
NLnet Labs
Description
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to way Unbound queues DNS requests, which makes it susceptible to DNSBomb attack. A remote attacker with ability to control the delay of the malicious authoritative answers can force Unbound to slowly accumulate pending answers for the spoofed addresses. When the authoritative answers become available to Unbound at the same time, Unbound starts serving all the accumulated queries. This results in large-sized, concentrated response bursts to the spoofed addresses.
Unbound itself is not vulnerable for DoS, rather it can be used to take part in a pulsing DoS amplification attack.
Remediation
Install updates from vendor's website.