CVE-2020-3509
CVE-2020-3509 is a high-severity vulnerability in Cisco Ios Xe with a CVSS 3.x base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-203.
Key facts
- Severity: High (CVSS 3.x base score 8.6)
- CVSS v2: 7.8
- EPSS exploit prediction: 1% (70th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-203
- Affected product: Cisco Ios Xe
- Published:
- Last modified:
Description
A vulnerability in the DHCP message handler of Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers could allow an unauthenticated, remote attacker to cause the supervisor to crash, which could result in a denial of service (DoS) condition. The vulnerability is due to insufficient error handling when DHCP version 4 (DHCPv4) messages are parsed. An attacker could exploit this vulnerability by sending a malicious DHCPv4 message to or through a WAN interface of an affected device. A successful exploit could allow the attacker to cause a reload of the affected device. Note: On Cisco cBR-8 Converged Broadband Routers, all of the following are considered WAN interfaces: 10 Gbps Ethernet interfaces 100 Gbps Ethernet interfaces Port channel interfaces that include multiple 10 and/or 100 Gbps Ethernet interfaces
Frequently asked questions
- What is CVE-2020-3509?
- A vulnerability in the DHCP message handler of Cisco IOS XE Software for Cisco cBR-8 Converged Broadband Routers could allow an unauthenticated, remote attacker to cause the supervisor to crash, which could result in a denial of service (DoS) condition. The vulnerability is due to insufficient error handling when DHCP version 4 (DHCPv4) messages are parsed. An attacker could exploit this vulnerability by sending a malicious DHCPv4 message to or through a WAN interface of an affected device. A successful exploit could allow the attacker to cause a reload of the affected device. Note: On Cisco cBR-8 Converged Broadband Routers, all of the following are considered WAN interfaces: 10 Gbps Ethernet interfaces 100 Gbps Ethernet interfaces Port channel interfaces that include multiple 10 and/or 100 Gbps Ethernet interfaces
- How severe is CVE-2020-3509?
- CVE-2020-3509 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2020-3509 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2020-3509?
- CVE-2020-3509 affects Cisco Ios Xe. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2020-3509?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2020-3509 published?
- CVE-2020-3509 was published on 2020-09-24 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:o:cisco:ios_xe:16.7\(1\):*:*:*:*:*:*:*
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