CVE-2018-0173
A vulnerability in the Cisco IOS Software and Cisco IOS XE Software function that restores encapsulated option 82 information in DHCP…
- Published
- Updated
- Reserved
- Assigned by
- cisco
Description
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.
Exploited in the wild
CISA lists this vulnerability in its Known Exploited Vulnerabilities catalog as Cisco IOS and IOS XE Software Improper Input Validation Vulnerability.
- Added
- 3 Mar 2022
- Fix due (US federal)
- 17 Mar 2022
- Used by ransomware
- Not known
Apply updates per vendor instructions.
Public exploit
An exploit or proof of concept is public: anyone can try it against an unpatched system. CISA's SSVC rates its exploitation: it is being exploited.
Timeline
ID reserved
By cisco
- 4 months later
· 4 months later
Published
- 4 years later
· 4 years later
Added to CISA KEV
Known exploited in the wild
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | High8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
| NVDNVD · Analyzed | 3.1 | High8.6 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 7.6% · top 5.4% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: active · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.6.
Weakness
Affected products
Cisco IOS and IOS XE
- affected Cisco IOS and IOS XE
References (7)
- https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-dhcpr2 (opens in a new tab)x_refsource_CONFIRMx_transferred
- 103545 (opens in a new tab)vdb-entryx_refsource_BIDx_transferred
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-04 (opens in a new tab)x_refsource_MISCx_transferred
- https://www.tenable.com/security/research/tra-2018-06 (opens in a new tab)x_refsource_MISCx_transferred
- 1040591 (opens in a new tab)vdb-entryx_refsource_SECTRACKx_transferred
- https://ics-cert.us-cert.gov/advisories/ICSA-18-107-05 (opens in a new tab)x_refsource_MISCx_transferred
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-0173 (opens in a new tab)government-resource
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- CISA KEV catalog (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2018-0173)Record last updated .