Cisco IOS XR Software Cisco Discovery Protocol Format String Vulnerability
Priority CRITICAL 97Exploited in the wildCWE-134Published · Updated
Key facts
- Attack vector
- Adjacent network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-134 and the CVSS impact.
Summary
A vulnerability in the Cisco Discovery Protocol implementation for Cisco IOS XR Software could allow an unauthenticated, adjacent attacker to execute arbitrary code or cause a reload on an affected device. The vulnerability is due to improper validation of string input from certain fields in Cisco Discovery Protocol messages. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet to an affected device. A successful exploit could allow the attacker to cause a stack overflow, which could allow the attacker to execute arbitrary code with administrative privileges on an affected device. Cisco Discovery Protocol is a Layer 2 protocol. To exploit this vulnerability, an attacker must be in the same broadcast domain as the affected device (Layer 2 adjacent).
Why it matters now
Exploitation Active In CISA KEV since 2021-11-03CISA due date 2022-05-03
EPSS 0.11685 96th percentileScored 2026-11-07
Fix Fixed Cisco IOS XR Software (Cisco): 6.6.3
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Active
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Cisco | Cisco IOS XR Software | before 6.6.3 | 6.6.3 | Patch available | CNA |
- Cisco IOS XR Software VendorCisco Affected before 6.6.3 Fixed in 6.6.3 Patch available CNA
CPE configurations NVD · 42
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* | 6.6.0 to before 6.6.12; 7.0.0 to before 7.0.2 | Vulnerable | Cisco |
| cpe:2.3:o:cisco:ios_xr:6.5.3:*:*:*:*:*:*:* | 6.5.3 | Vulnerable | Cisco |
| cpe:2.3:h:cisco:asr_9000v:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9001:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9006:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9010:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9901:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9904:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9906:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9910:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
- cpe:2.3:o:cisco:ios_xr:*:*:*:*:*:*:*:* Versions 6.6.0 to before 6.6.12; 7.0.0 to before 7.0.2 Vulnerable ·Cisco
- cpe:2.3:o:cisco:ios_xr:6.5.3:*:*:*:*:*:*:* Versions 6.5.3 Vulnerable ·Cisco
- cpe:2.3:h:cisco:asr_9000v:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9001:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9006:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9010:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9901:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9904:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9906:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9910:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
Show 32 more CPE
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:h:cisco:asr_9912:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9922:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540-12z20g-sys-a:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540-12z20g-sys-d:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540-24z8q2c-sys:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540-28z4c-sys-a:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540-28z4c-sys-d:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540-acc-sys:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540x-12z16g-sys-a:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540x-12z16g-sys-d:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540x-16z4g8q2c-a:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540x-16z4g8q2c-d:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_540x-acc-sys:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_5501:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_5501-se:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_5502:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_5502-se:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_5508:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_5516:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:xrv_9000:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:o:cisco:ios_xr:5.2.5:*:*:*:*:*:*:* | 5.2.5 | Vulnerable | Cisco |
| cpe:2.3:h:cisco:ncs_6000:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:ncs_6008:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:o:cisco:ios_xr:6.4.2:*:*:*:*:*:*:* | 6.4.2 | Vulnerable | Cisco |
| cpe:2.3:h:cisco:asr_9000:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9903:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:asr_9920:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:h:cisco:crs-x:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:o:cisco:ios_xr:6.6.25:*:*:*:*:*:*:* | 6.6.25 | Vulnerable | Cisco |
| cpe:2.3:h:cisco:ncs_560:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
| cpe:2.3:o:cisco:ios_xr:7.0.1:*:*:*:*:*:*:* | 7.0.1 | Vulnerable | Cisco |
| cpe:2.3:h:cisco:ncs_540l:-:*:*:*:*:*:*:* | not specified by NVD | Running on | Cisco |
- cpe:2.3:h:cisco:asr_9912:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9922:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540-12z20g-sys-a:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540-12z20g-sys-d:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540-24z8q2c-sys:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540-28z4c-sys-a:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540-28z4c-sys-d:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540-acc-sys:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540x-12z16g-sys-a:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540x-12z16g-sys-d:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540x-16z4g8q2c-a:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540x-16z4g8q2c-d:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_540x-acc-sys:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_5501:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_5501-se:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_5502:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_5502-se:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_5508:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_5516:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:xrv_9000:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:o:cisco:ios_xr:5.2.5:*:*:*:*:*:*:* Versions 5.2.5 Vulnerable ·Cisco
- cpe:2.3:h:cisco:ncs_6000:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:ncs_6008:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:o:cisco:ios_xr:6.4.2:*:*:*:*:*:*:* Versions 6.4.2 Vulnerable ·Cisco
- cpe:2.3:h:cisco:asr_9000:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9903:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:asr_9920:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:h:cisco:crs-x:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:o:cisco:ios_xr:6.6.25:*:*:*:*:*:*:* Versions 6.6.25 Vulnerable ·Cisco
- cpe:2.3:h:cisco:ncs_560:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
- cpe:2.3:o:cisco:ios_xr:7.0.1:*:*:*:*:*:*:* Versions 7.0.1 Vulnerable ·Cisco
- cpe:2.3:h:cisco:ncs_540l:-:*:*:*:*:*:*:* Versions not specified by NVD Running on ·Cisco
Remediation
- Fix · CNA Cisco IOS XR Software (Cisco) Fixed in 6.6.3
Timeline
- 2021-11-03 Added to CISA KEV
- 2026-10-02 Threatist record created from CVE-2020-3118
- 2026-10-03 Alias added: GHSA-f7vj-6cqm-9xgc
References
More Cisco Ios Xr vulnerabilities
- TI-2018-00135 Memory corruption in Cisco IOS, IOS XE, and IOS XR KEVCVSS 3.1HIGH 8.8
- TI-2020-03113 Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerabilities KEVCVSS 3.1HIGH 8.6
- TI-2020-03110 Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerability KEVCVSS 3.1HIGH 8.6
- TI-2018-00142 Memory corruption in Cisco IOS, IOS XE, and IOS XR KEVCVSS 3.1HIGH 8.0
- TI-2023-23979 The HTTP/2 protocol allows a denial of service (server resource consumption) because… KEVCVSS 3.1HIGH 7.5
- TI-2016-05497 The server IKEv1 implementation in Cisco IOS 12.2 through 12.4 and 15.0 through 15.6, IOS… KEVCVSS 3.1HIGH 7.5
Sources
- CVE-2020-3118 · CVE Program
- CVE-2020-3118 · NVD
- CISA Known Exploited Vulnerabilities
- FIRST EPSS
- GHSA-f7vj-6cqm-9xgc · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences