CVE-2016-6421

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

Score 5.3 from GitHub Security Advisory published 2022-05-17. NVD baseline CVSS 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 2%CVSS: 5.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Cisco IOS XR 5.2.2 allows remote attackers to cause a denial of service (process restart) via a crafted OSPF Link State Advertisement (LSA) update, aka Bug ID CSCvb05643.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity53% × 45%
Exploitation2% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
2%
EPSS %ILE
73%
KEV
Not listed

Published

October 5, 2016

Last Modified

June 17, 2026

References (6)

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 41× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-26 14:50 UTCEPSS rescore
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Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2016-6421?
CVE-2016-6421 is a medium vulnerability published on October 5, 2016. Cisco IOS XR 5.2.2 allows remote attackers to cause a denial of service (process restart) via a crafted OSPF Link State Advertisement (LSA) update, aka Bug ID CSCvb05643.
When was CVE-2016-6421 disclosed?
CVE-2016-6421 was first published in the National Vulnerability Database on October 5, 2016, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2016-6421 actively exploited?
CVE-2016-6421 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 2% probability of exploitation in the next 30 days, which ranks it in the top 26.8% of all scored CVEs.
What is the CVSS score of CVE-2016-6421?
CVE-2016-6421 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2016-6421?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2016-6421, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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