vciy

CVE-2021-1611

INDEX BUILT · 2026-09-20

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Cisco IOS XE Software for Catalyst 9800 Series Wireless Controllers EoGRE Denial of Service Vulnerability

CVE-2021-16114 of 4 sources documented this
24

rank 24 = 0 + 22 + 0 + 2 + 0

rank@v1 · backlog

Someone is already using it

CISA KEV catalog · public proof-of-concept · FIRST EPSS

EPSS 0.01328  ·  without this subject the record ranks 24

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 8.6, from NVD  ·  without this subject the record ranks 2

It is getting worse, not staying still

FIRST EPSS series, rescorings and bad loads removed

no persisting rise in 365 days  ·  without this subject the record ranks 24

How much of the world it touches

NVD CPE configurations

1 product in the CPE ranges  ·  without this subject the record ranks 22

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 24

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$40,600over the next 30 days, if this record is yours
Movementno material movementthe record holds only daily drift and scoring model releases
Basisassumeda published average, not your estate

$40,600 = $4.99M incident cost x 0.6121449559255632 exposure x 0.01328 likelihood

udv@v1 · unaudited · wrong for you until you say what you run

$4.99M is the cost of a breach that happened, from IBM Cost of a Data Breach Report 2026, global average. It is not the value of any asset of yours. That average already covers breaches of every severity, so scaling it by exposure understates a partial-impact record. That is an assumption, not a measurement. Your own asset value goes in the decision record.

Hindsight · the state

0.01328EPSSNOT IN KEVas of 2026-09-20
Severity8.6 HIGHreceipt
Harmunauthenticated · networkreceipt
Exploitationnone in held sources
Defenseunaffected versions publishedreceipt
Movementrisenreceipt
PLATEAU10Minimal movement since 2021-09-23, 1758 days at 0.01, as of 2026-07-17. arc-rules@v1

Foresight · where to check next

Cisco IOSCisco IOS and IOSCisco IOS1611

This record is one instance of CWE-399. The index holds 2695 prior instances of this class, 11 KEV-listed. The nearest of its KEV-listed records are drawn beside this. taxonomy@v1

Full pattern panel

Prior records in this weakness class. Each is its own record, dated and receipted.
Color is a claim, not decoration:the hostile worldthe defenseno signalspoke length is how much of the record matches, not how bad it is

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Harm, if it fires from the vector and the weakness

Written for the ticket you're about to file.

Reachnetwork-reachable · no privileges required · no user interaction · low attack complexityreceipt
ImpactComplete availability loss, with impact beyond the vulnerable componentreceipt
Scored fromCVSS v3.1 · the CNA's vectorreceipt
Weakness classCWE-399receipt
Published consequencesMITRE publishes no common consequences for this weakness.[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

The fix, and how long it's been waiting.

First unaffected version, by branchios xe 17.3.1receipt
Patch available sinceNo dated patch-availability record in held sources. The index holds reference URLs without dates and only the current revision of the CVE record, so the day a fix first existed cannot be derived. Only the versions it landed in.

Exploit Status & Known PoCs a ladder, not a score

Current rung: Nothing observed in held sources.

  • RUNG 1Nothing observed in held sources
  • RUNG 2Proof-of-concept published
  • RUNG 3Exploited in the wild · CISA KEV listed
  • RUNG 4Ransomware campaign use known

Authority who says so

CVSS, the CNA8.6 HIGHreceipt
CVSS, NVD8.6 HIGHreceipt
Exploit probability0.01328 · top 30% of all CVEsreceipt
Blast breadth1 product across 1 vendorderived
Assigned byciscoreceipt
Recorded changes23 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productCisco IOS XE Softwarereceipt
Published rangescisco ios xe < 17.3.1receipt

A rung lights from a row in the index, never from an assessment. "Held sources" is the true scope of the claim: this index reads the CVE record, NVD, CISA KEV, FIRST's EPSS and public proof-of-concept repositories, and it does not observe attacks.

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Attack path

Unauthenticated network requestno credentials, no interactionCisco IOS XE SoftwareCWE-399 weaknessAdjacent componentsscope changeAvailability lossA:Hexploits CWE-399scope changedata compromise

What it is stated by the CNA

A vulnerability in Ethernet over GRE (EoGRE) packet processing of Cisco IOS XE Wireless Controller Software for the Cisco Catalyst 9800 Family Wireless Controller, Embedded Wireless Controller, and Embedded Wireless on Catalyst 9000 Series Switches could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper processing of malformed EoGRE packets. An attacker could exploit this vulnerability by sending malicious packets to the affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition. receipt

NVD's analysis a second authority

severity
8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
weakness
CWE-399
affected versions
cisco ios xe < 17.3.1
also scored by
[email protected] 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

check it yourself tools.cisco.com receipt

Movement the material steps

23 Sep 20210.00651
7 Mar 20230.00131 · scoring model v2023.03.01
17 Mar 20250.00408 · scoring model v2025.03.14
15 Jun 20260.01285 · scoring model v2026.06.15
17 Jul 20260.01328
Show all 23 observations
23 Sep 20210.00651
6 Jan 20220.02857
4 Feb 20220.04499
1 Apr 20220.01055
7 Mar 20230.00131
15 Apr 20230.00138
28 Apr 20240.00140
7 Jun 20240.00160
17 Mar 20250.00408
19 Mar 20250.00479
29 Mar 20250.00652
30 Mar 20250.00479
14 Jul 20250.00491
30 Jul 20250.00442
1 Oct 20250.00491
27 Oct 20250.00442
28 Oct 20250.00491
18 Nov 20250.00679
21 Nov 20250.00491
27 Dec 20250.00442
28 Dec 20250.00491
15 Jun 20260.01285
17 Jul 20260.01328

23 observations held. A highlighted step crossed a promotion threshold. A step marked with a scoring model moved because the instrument was replaced, not because the vulnerability changed. receipt

The full biography

EPSS 0.01328Published2021-09-23Index as of2026-07-17

The record had been public for 4 years, 9 months when this index was last written.

Published 2021-09-23 receipt · Index as of 2026-07-17 derived

The pattern, elsewhere

This record is one instance of CWE-399. The index holds 2695 prior instances of this class, 11 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]

CVE-2018-0154 · Cisco IOSmatches 8 of 9KEV listed · 2018receipt
CVE-2018-0156 · Cisco IOS and IOS XEmatches 8 of 9KEV listed · 2018receipt
CVE-2017-12231 · Cisco IOSmatches 8 of 9KEV listed · 2017receipt
CVE-2017-12237 · Cisco IOS and IOS XEmatches 8 of 9KEV listed · 2017receipt
CVE-2017-6627 · Cisco IOS and Cisco IOS XEmatches 8 of 9KEV listed · 2017receipt
CVE-2018-0161 · Cisco IOSmatches 7 of 9KEV listed · 2018receipt

"Matches n of m" counts the attributes the two records can both be compared on: the CVSS metrics they share a version of, any weakness class beyond this one, and the vendor. fit-rules@v1

2695 records in this class held. The six above are drawn from the ones CISA has listed as exploited, ranked by how much of the record matches this one. That is why every one of them is KEV-listed: the pool is, so the colour on those spokes says nothing the pool has not already said.

No curated product neighbourhood is held for this product, so the records above are the nearest this index can name. The neighbourhood table covers a small set of products and is extended by hand.

Siblings and hubs

Records related to this one

Its defect family

cisco ios xe software

Of the 13 records in this family, this is the only one whose title names 9800 eogre.

Grouped by shared product and weakness, not by shared vulnerability. Each record's own state is on its own page.

Family membership: computed, pro@dim2000

This record is one of a group, and the group's page describes all of them. This page is kept and dated, and the defect family's own page is the one we offer for indexing: the whole group.

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What usually comes next

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