CVE-2021-34795

CRITICALNVD 10.010.0—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 10.0 under NVD CVSS v3. EPSS exploit probability: 1.7% (76th percentile of EPSS-scored CVEs). GitHub Security Advisory enrichment pending alignment with NVD CVSS.

Triggered by: NVD CVSS baseline
Sources: epss, ghsa, nvd
10.0EG
EchelonGraph verdictPlan mitigationSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1.7%CVSS: 10.0Exploit: None knownExposed services: Not assessed

A fix is referenced (a reference tagged "Patch", often a source commit), but no release containing it is confirmed — find the release that contains it; until it is applied, mitigate (WAF / firewall / segmentation).

Multiple vulnerabilities in the web-based management interface of the Cisco Catalyst Passive Optical Network (PON) Series Switches Optical Network Terminal (ONT) could allow an unauthenticated, remote attacker to perform the following actions: Log in with a default credential if the Telnet protocol is enabled Perform command injection Modify the configuration For more information about these vulnerabilities, see the Details section of this advisory.

CVSS v3
10.0
EG Score
10.0CRITICALmedium confidence
EG Risk
61
EG Risk 61/100CISA SSVC

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
Severity100% × 45%
Exploitation2% × 40%
Automatability100% × 15%
CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).
Action: A fix is referenced, but no release containing it is confirmed. Check the referenced fix and the vendor's advisory for a release that contains it and apply that within your standard update timelines at low or medium mission impact and sooner than that at high; until then, restrict network exposure of the affected system or apply the vendor's mitigation.
EPSS PROB
1.7%
EPSS %ILE
77th
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).

A fix is referenced, but no release containing it is confirmed. Check the referenced fix and the vendor's advisory for a release that contains it and apply that within your standard update timelines at low or medium mission impact and sooner than that at high; until then, restrict network exposure of the affected system or apply the vendor's mitigation.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

November 4, 2021

Last Modified

November 21, 2024

Advisory Details (1)

Auto-updated Oct 10, 2026
Fix referenced — no release confirmed yet.
generic

Cisco Catalyst PON Series Switches Optical Network Terminal Vulnerabilities

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-catpon-multivulns-CE3DSYGr

Weakness Classification(3)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 33× 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 181 total refreshes for this CVE.

  1. 2026-10-10 19:56 UTCEPSS rescore
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  10. 2026-09-30 15:37 UTCEG score recompute
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  59. 2026-07-23 02:01 UTCEG score recompute
  60. 2026-07-22 22:48 UTCEG score recompute▲ 0.20
  61. 2026-07-22 14:06 UTCEPSS rescore
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  73. 2026-07-15 16:55 UTCEPSS rescore
  74. 2026-07-15 01:58 UTCEPSS rescore
  75. 2026-07-13 22:27 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2021-34795?
CVE-2021-34795 is a critical vulnerability published on November 4, 2021. Multiple vulnerabilities in the web-based management interface of the Cisco Catalyst Passive Optical Network (PON) Series Switches Optical Network Terminal (ONT) could allow an unauthenticated, remote attacker to perform the following actions: Log in with a default credential if the Telnet protocol…
When was CVE-2021-34795 disclosed?
CVE-2021-34795 was first published on November 4, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-34795 actively exploited?
CVE-2021-34795 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1.7% probability of exploitation in the next 30 days (77th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2021-34795?
CVE-2021-34795 has a CVSS v3 base score of 10.0 (NVD).
How do I remediate CVE-2021-34795?
A fix for CVE-2021-34795 is referenced (a reference tagged "Patch", often a source commit), but EchelonGraph has no release containing it on record. Check that reference and the vendor's advisory for a release that contains the fix and update to it; until then, restrict network exposure of the affected system or apply the vendor's mitigation.

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