#VU53609 Input validation error in DHCP - CVE-2021-25217

Vulnerability identifier: #VU53609

Vulnerability risk: Medium

CVSSv4.0: 1.3 [CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-25217

CWE-ID: CWE-20

Exploitation vector: Local network

Exploit availability: No

Vulnerable software:
DHCP
Server applications / Other server solutions

Vendor: ISC

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack or gain access to sensitive information.

The vulnerability exists due to insufficient validation of options data stored in DHCP leases. A remote attacker can pass specially crafted input to the application and perform a denial of service (DoS) attack or gain access to sensitive information.

Both dhcpd and dhclient are affected by the vulnerability.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

DHCP: 3.0 - 3.0.6, 3.1-ESV-R1 - 3.1.3, 4.1-ESV-R1 - 4.1-esv, 4.4.0 b1 - 4.4.2

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External links
https://kb.isc.org/docs/cve-2021-25217

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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 local network (LAN).

Is there known malware, which exploits this vulnerability?

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