CVE-2021-34753

MEDIUMNVD 5.85.8—
EchelonGraph scoreMEDIUM confidence

Score 5.8 from GitHub Security Advisory published 2024-11-15. NVD baseline CVSS 5.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
5.8
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 5.8Exploit: NoneExposed: 0

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

A vulnerability in the payload inspection for Ethernet Industrial Protocol (ENIP) traffic for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured rules for ENIP traffic. This vulnerability is due to incomplete processing during deep packet inspection for ENIP packets. An attacker could exploit this vulnerability by sending a crafted ENIP packet to the targeted interface. A successful exploit could allow the attacker to bypass configured access control and intrusion policies that should trigger and drop for the ENIP packet.

CVSS v3
5.8
EG Score
5.8(medium)
EG Risk
41(Track)
EG Risk 41/100SSVC: 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
Severity58% × 45%
Exploitation1% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
47.2%
KEV
Not listed

Published

November 15, 2024

Last Modified

August 7, 2025

References (1)

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 15× in last 7d / 44× 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.

Showing the most recent 100 of 102 total refreshes for this CVE.

  1. 2026-07-24 14:15 UTCEPSS rescore
  2. 2026-07-23 14:16 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2021-34753?
CVE-2021-34753 is a medium vulnerability published on November 15, 2024. A vulnerability in the payload inspection for Ethernet Industrial Protocol (ENIP) traffic for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured rules for ENIP traffic. This vulnerability is due to incomplete processing during deep…
When was CVE-2021-34753 disclosed?
CVE-2021-34753 was first published in the National Vulnerability Database on November 15, 2024, with the most recent update on August 7, 2025. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-34753 actively exploited?
CVE-2021-34753 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 47.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2021-34753?
CVE-2021-34753 has a CVSS v3 base score of 5.8 (NVD).
How do I remediate CVE-2021-34753?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-34753, 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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