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PatchSiren cyber security CVE debrief

CVE-2020-3118 Cisco CVE debrief

CVE-2020-3118 is a Cisco IOS XR software vulnerability described as a Discovery Protocol format string issue. It is listed in CISA’s Known Exploited Vulnerabilities (KEV) catalog, which means defenders should treat it as an active risk and prioritize vendor-recommended updates.

Vendor
Cisco
Product
IOS XR
CVSS
HIGH 8.8
CISA KEV
Listed
Original CVE published
2021-11-03
Original CVE updated
2021-11-03
Advisory published
2021-11-03
Advisory updated
2021-11-03

Who should care

Organizations running Cisco IOS XR, especially any Internet- or partner-facing network infrastructure, should prioritize this issue. Security and network operations teams should also care because CISA has already classified it as known exploited.

Technical summary

The supplied sources identify a format string vulnerability in Cisco IOS XR’s Discovery Protocol handling. Beyond the title and KEV entry, the corpus does not provide implementation details, affected versions, or impact specifics. What is clear from the official CISA KEV listing is that the issue has been observed in real-world exploitation and should be addressed by applying vendor updates.

Defensive priority

High. CISA KEV inclusion indicates known exploitation and makes this a priority remediation item over unexploited advisories.

Recommended defensive actions

  • Apply Cisco-provided updates or mitigations per vendor instructions as soon as possible.
  • Inventory Cisco IOS XR deployments to determine exposure and identify affected assets.
  • Prioritize externally reachable or business-critical IOS XR devices for remediation first.
  • Verify that patching or mitigation was completed before the KEV due date and confirm current compliance.
  • Monitor Cisco and CISA advisories for any version-specific guidance or updated remediation notes.

Evidence notes

The source corpus includes the CISA KEV record for this CVE with vendorProject Cisco, product IOS XR, vulnerabilityName "Cisco IOS XR Software Discovery Protocol Format String Vulnerability," dateAdded 2021-11-03, and dueDate 2022-05-03. The corpus also includes official CVE.org and NVD links, but no additional advisory text or version scope. Timing context in this debrief uses the supplied CVE/source dates and KEV fields only.

Sources and references

Verified primary and authoritative sources

  • CVE-2020-3118 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2020-3118

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2020-3118 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2020-3118

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

    cisa_kev

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.