CVE-2020-3118
Memory Safety in Cisco Ios Xr 6.6.0 – 6.6.12
Raw vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2020-3118 is a high-severity Use of Externally-Controlled Format String (CWE-134) vulnerability in Cisco Ios Xr. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique LSASS Memory (T1003.001); ranked in the top 4% of CVEs by exploit likelihood; CISA has added it to the Known Exploited Vulnerabilities catalog; a public proof-of-concept is referenced.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
A vulnerability in the Cisco Discovery Protocol implementation within Cisco IOS XR Software stems from improper validation of string input in certain CDP message fields. This flaw, tracked under CWE-134 and CWE-787, can trigger a stack overflow when processing crafted packets. The affected component is the Layer 2 CDP handler on IOS XR devices, which runs with elevated privileges.
An unauthenticated attacker positioned on the same broadcast domain can exploit the issue by transmitting a single malicious CDP packet to an adjacent device. Successful exploitation yields arbitrary code execution with administrative rights or triggers a device reload, corresponding to the CVSS 8.8 vector AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
The Cisco Security Advisory cisco-sa-20200205-iosxr-cdp-rce details the flaw and available fixes, while the CISA Known Exploited Vulnerabilities catalog lists CVE-2020-3118 as actively used in the wild. Public exploit code has also appeared on Packet Storm.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2020-24389
Vulnerability Data
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…
more
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).
- CWE(s)
- KEV Date Added
- 03 November 2021
Related Threats
Threat-Actor AttributionAI
MITRE ATT&CK Enterprise Techniques
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Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Out-of-bounds writes that corrupt control flow or inject shellcode are rendered non-executable by the same memory protections.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Vulnerability identification can discover existing format-string flaws but does not prevent their introduction.
Patching or replacing vulnerable software directly eliminates known instances of this coding weakness.
Secure SDLC practices directly prevent external format strings via code review, static analysis, and safe APIs.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.