#VU53031 Reachable Assertion in Unbound - CVE-2019-25037

Vulnerability identifier: #VU53031

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-25037

CWE-ID: CWE-617

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Unbound
Server applications / DNS servers

Vendor: NLnet Labs

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a reachable assertion within the dname_pkt_copy() function. A remote attacker can send specially crafted packets to the DNS server, trigger an assertion failure and perform a DoS attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Unbound: 1.0.0 - 1.9.4

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External links
https://ostif.org/our-audit-of-unbound-dns-by-x41-d-sec-full-results/
https://lists.debian.org/debian-lts-announce/2021/05/msg00007.html
https://security.netapp.com/advisory/ntap-20210507-0007/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.