CVE-2020-3511 json
Cisco IOS and IOS XE Software ISDN Q.931 Denial of Service Vulnerability
published 2020-09-24 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-24782
- cvss
- 7.4
- version 3.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 37%
- public exploits
- 0
- none known
Summary
A vulnerability in the ISDN subsystem of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, adjacent attacker to cause a reload of an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to insufficient input validation when the ISDN Q.931 messages are processed. An attacker could exploit this vulnerability by sending a malicious ISDN Q.931 message to an affected device. A successful exploit could allow the attacker to cause the process to crash, resulting in a reload of the affected device.
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 23 mo ago
Exploit prediction
0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.0 | 7.4 | CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
| NVD | 3.1 | 7.4 | CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H |
| NVD | 2.0 | 6.1 | AV:A/AC:L/Au:N/C:N/I:N/A:C |
Affected products
- Cisco Cisco IOS
Classification
- Weakness
-
- CWE-20 Improper Input Validation
- Technology feeds
References
Sources
- CVE List CVE-2020-3511
- NVD CVE-2020-3511
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.