Cisco IOS XR Software Discovery Protocol Format String Vulnerability
Cisco · IOS XR
A flaw in the Cisco Discovery Protocol implementation of Cisco IOS XR Software, caused by improper validation of string input from certain fields in CDP messages, allows arbitrary code execution or a device reload. An unauthenticated attacker in the same broadcast domain (Layer 2 adjacent) can exploit it by sending a malicious CDP packet to the affected device, which can cause a stack overflow that runs code with administrative privileges.
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).
- Exploited
- Yes, in CISA KEV
- Reports
- 0
- Tactics
- 2/15
How an attack unfolds
Based on MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. mappings. Select a step to see the evidence.Exploitation timelineDated milestones for a CVE: when it was disclosed, when exploit code became public, when exploitation was confirmed, and when threat reports named it.
First seen exploited 8 months after disclosure.
- Disclosedday 0
- First seen exploitedVulnCheck KEV evidence+8 mo
- Added to CISA KEVEU database agrees+21 mo
CISA KEV listing is when exploitation was confirmed, not necessarily the first attack.
MITRE ATT&CKA public catalogue of the techniques attackers use, maintained by MITRE. Patchfirst uses it to describe what attackers do with a vulnerability. techniques
2 TechniqueOne specific attacker behaviour in MITRE ATT&CK, such as T1190 “Exploit Public-Facing Application”. IDs with a dot, like T1059.004, are sub-techniques., grouped by TacticThe attacker’s goal at a stage of an attack in MITRE ATT&CK, such as Initial Access or Persistence. Each technique belongs to one or more tactics. in kill-chain order, 2 cited passages 2ExecutionTA0002
Arbitrary code execution with admin privileges
could allow the attacker to execute arbitrary code with administrative privileges
Lateral MovementTA0008
Adjacent network packet exploits remote service
An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol packet
Detection
0 rules for this CVE · 110 general rules for its techniquesRules for this CVE
0Sigma ruleAn open, vendor-neutral detection rule for log data. Security teams convert Sigma rules into searches for their own SIEM. that reference CVE-2020-3118 directly.CVE-specific rules are not available in this build. Search SigmaHQ ↗
General rules for this CVE’s techniques
These detect the technique in general, not this specific vulnerability.
Exploitation of Remote ServicesT121015 general rules
- Zerologon Exploitation Using Well-known Toolscriticalstable
- Audit CVE Eventcriticaltest
- WannaCry Ransomware Activitycriticaltest
- OMIGOD HTTP No Authentication RCE - CVE-2021-38647highstable
- Exploitation Attempt Of CVE-2020-1472 - Execution of ZeroLogon PoChightest
- Exploitation Attempt Of CVE-2023-46214 Using Public POC Codehightest
- HackTool - SharpWSUS/WSUSpendu Executionhightest
- Possible Exploitation of Exchange RCE CVE-2021-42321hightest
Command and Scripting InterpreterT105995 general rules
- HackTool - Sliver C2 Implant Activity Patterncriticaltest
- Lazarus Group Activitycriticaltest
- REvil Kaseya Incident Malware Patternscriticaltest
- Turla Group Lateral Movementcriticaltest
- Windows Defender AMSI Trigger Detectedhighstable
- Windows Defender Threat Detectedhighstable
- Abusable DLL Potential Sideloading From Suspicious Locationhightest
- Add Insecure Download Source To Wingethightest
Sigma rules © SigmaHQ, Detection Rule License 1.1; linked, not reproduced.
What security researchers reported
Not named in any threat report yetAlso mentioned in 50 community threat pulses (AlienVault OTX)
Weaker evidencePulses are indicator collections that anyone can publish. A mention is not confirmation of exploitation.
- Actively_Exploited_Kev | Oct 29, 202628 Oct 2026
- Actively_Exploited_Kev | Oct 28, 202627 Oct 2026
- Actively_Exploited_Kev | Oct 27, 202626 Oct 2026
- Actively_Exploited_Kev | Oct 24, 202623 Oct 2026
- Actively_Exploited_Kev | Oct 23, 202622 Oct 2026
- Actively_Exploited_Kev | Oct 22, 202621 Oct 2026
- 44 more on OTX