November 13, 2026 Follow Egret
CVE-2020-3118 · CVE record: PUBLISHED

Cisco IOS XR Software Cisco Discovery Protocol Format String Vulnerability

Cisco Cisco IOS XR Software

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).

Exploitation evidence

Known exploited · CISA KEV listed

Added 2021-11-03. Ransomware campaign use: Unknown.

CISA required action: Apply updates per vendor instructions.

CISA due date: 2022-05-03. This is the catalog’s deadline, not an assessment of your organization’s exposure.

KEV checked 13 Nov 2026, 00:20 Jerusalem · Original catalog ↗

Reported products and versions

Cisco / Cisco IOS XR Software

Default status: Not specified

  • affected: unspecified to < 6.6.3 (custom)

Fixes and workarounds

No explicit solution text in the downloaded CVE record. Consult the vendor advisory; unaffected version ranges are shown above as reported, not inferred as a patch recommendation.

Sources and related reporting

CVE Program record ↗ · Download tracked evidence as JSON

Observed change timeline

History begins when Egret first downloads each source. It is not the complete upstream CVE history.

12 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-12",
  "epss": 0.11685,
  "percentile": 0.96119
}
10 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-10",
  "epss": 0.11685,
  "percentile": 0.96093
}
09 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-09",
  "epss": 0.11685,
  "percentile": 0.96089
}
08 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-08",
  "epss": 0.11685,
  "percentile": 0.96087
}
07 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-07",
  "epss": 0.11685,
  "percentile": 0.96084
}
06 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-06",
  "epss": 0.11685,
  "percentile": 0.96078
}
06 Nov 2026, 06:20 Jerusalem · CVE Program record changed

Stored CNA snapshot at this observation.

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05 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-05",
  "epss": 0.11685,
  "percentile": 0.96076
}
04 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-04",
  "epss": 0.11685,
  "percentile": 0.96072
}
03 Nov 2026, 18:20 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-03",
  "epss": 0.11685,
  "percentile": 0.96065
}
03 Nov 2026, 02:22 Jerusalem · EPSS observation updated

Stored EPSS snapshot at this observation.

{
  "date": "2026-11-02",
  "epss": 0.11685,
  "percentile": 0.9606
}
03 Nov 2026, 02:22 Jerusalem · CISA KEV status changed

Stored KEV snapshot at this observation.

{
  "cveID": "CVE-2020-3118",
  "cwes": [
    "CWE-134"
  ],
  "dateAdded": "2021-11-03",
  "dueDate": "2022-05-03",
  "forensicTriage": "No",
  "knownRansomwareCampaignUse": "Unknown",
  "notes": "https://nvd.nist.gov/vuln/detail/CVE-2020-3118",
  "product": "IOS XR",
  "requiredAction": "Apply updates per vendor instructions.",
  "shortDescription": "Cisco IOS XR improperly validates string input from certain fields in Cisco Discovery Protocol messages. Exploitation could allow an unauthenticated, adjacent attacker to execute code with administrative privileges or cause a reload on an affected device.",
  "vendorProject": "Cisco",
  "vulnerabilityName": "Cisco IOS XR Software Discovery Protocol Format String Vulnerability"
}
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