Administrative code execution via attacker-controlled CDP format string
Published Feb 5, 2020 · Updated Oct 21, 2025
Format string injection in Cisco IOS XR Software before 6.6.3 allows attackers to execute administrative code or reload devices. The CDP parser passes attacker-controlled Device ID, Port ID, and other string fields as the format parameter to sprintf, enabling controlled out-of-bounds stack writes. Exploitation requires CDP enabled globally and on at least one interface plus Layer 2 adjacency in the same broadcast domain; IOS XR disables CDP by default.
Summary
What happened
Format string injection in Cisco IOS XR Software before 6.6.3 allows attackers to execute administrative code or reload devices. The CDP parser passes attacker-controlled Device ID, Port ID, and other string fields as the format parameter to sprintf, enabling controlled out-of-bounds stack writes. Exploitation requires CDP enabled globally and on at least one interface plus Layer 2 adjacency in the same broadcast domain; IOS XR disables CDP by default.
The record
- CVE
- CVE-2020-3118
- Published
- Feb 5, 2020
- Updated
- Oct 21, 2025
- Vendor
- ClamAV
- Product
- Cisco IOS XR Software
- Classifications
- CWE-134, CWE-787, T1210
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Feb 5, 2020CVE publishedPublication date reported by the CVE source.
- Oct 21, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=unspecified <6.6.3
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Reported exploitation
- CISA Known Exploited Vulnerabilities catalog listingknown exploited catalog
- Cisco PSIRT reports attempted exploitation in the wildreported exploitation
Technologies
Your stack
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Your stack
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