Known exploited vulnerability
CVE-2018-0173
The short answer
CVE-2018-0173 affects n/a Cisco IOS and IOS XE and is rated high (CVSS 8.6). CISA added it to the Known Exploited Vulnerabilities catalog on 2022-03-03: attackers are using it, so patch it first.
What it is
A vulnerability in the Cisco IOS Software and Cisco IOS XE Software function that restores encapsulated option 82 information in DHCP Version 4 (DHCPv4) packets could allow an unauthenticated, remote attacker to cause an affected device to reload, resulting in a Relay Reply denial of service (DoS) condition. The vulnerability exists because the affected software performs incomplete input validation of encapsulated option 82 information that it receives in DHCPOFFER messages from DHCPv4 servers. An attacker could exploit this vulnerability by sending a crafted DHCPv4 packet to an affected device, which the device would then forward to a DHCPv4 server. When the affected software processes the option 82 information that is encapsulated in the response from the server, an error could occur. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition. Cisco Bug IDs: CSCvg62754.
Weakness: CWE-20.
Severity
8.6 high
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
Exploited (CISA KEV)
Yes, since Mar 3, 2022
Federal due date Mar 17, 2022
EPSS, next 30 days
7.6%
Higher than 95% of scored CVEs
How it can be exploited
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Changed
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
What CISA says to do
Apply updates per vendor instructions.
Affected products
Cisco IOS and IOS XE. NVD's record lists the exact affected versions.
References
- ics-cert.us-cert.gov/advisories/ICSA-18-107-04 Third Party AdvisoryUS Government Resource
- ics-cert.us-cert.gov/advisories/ICSA-18-107-05 Third Party AdvisoryUS Government Resource
- tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2 Vendor Advisory
- www.tenable.com/security/research/tra-2018-06 Third Party Advisory
- ics-cert.us-cert.gov/advisories/ICSA-18-107-04 Third Party AdvisoryUS Government Resource
- ics-cert.us-cert.gov/advisories/ICSA-18-107-05 Third Party AdvisoryUS Government Resource
- tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2 Vendor Advisory
- www.tenable.com/security/research/tra-2018-06 Third Party Advisory
- www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-0173 US Government Resource
Questions
Is CVE-2018-0173 being exploited?
Yes. CISA added CVE-2018-0173 to its Known Exploited Vulnerabilities catalog on 2022-03-03, with a federal remediation due date of 2022-03-17.
How do I fix CVE-2018-0173?
CISA's required action: Apply updates per vendor instructions.
From NVD, CISA KEV, FIRST EPSS and OSV.dev, checked . Status on NVD: Analyzed. The description is NVD's text, quoted as published.
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