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CVE-2019-1687

INDEX BUILT · 2026-09-20

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Cisco Adaptive Security Appliance Software and Firepower Threat Defense Software TCP Proxy Denial of Service Vulnerability

CVE-2019-16874 of 4 sources documented this
27

rank 27 = 1 + 19 + 0 + 7 + 0

rank@v1 · scheduled

Someone is already using it

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

EPSS 0.02900  ·  without this subject the record ranks 26

What it costs you if it fires

NVD CVSS base score, then the CNA's own

CVSS 7.5, from NVD  ·  without this subject the record ranks 8

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 27

How much of the world it touches

NVD CPE configurations

7 products in the CPE ranges  ·  without this subject the record ranks 20

Someone else already set the date

CISA KEV remediation due date

no CISA due date  ·  without this subject the record ranks 27

Unaudited dollar value2 of 3 inputs carry a receipt
Exposure$88,600over 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

$88,600 = $4.99M incident cost x 0.6121449559255632 exposure x 0.029 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

0.029EPSSNOT IN KEVas of 2026-09-20
Severity6.8 MEDIUMreceipt
Harmunauthenticated · networkreceipt
Exploitationnone in held sources
Defensefix version namedreceipt
Movementscoring model changedreceipt
PLATEAU10Minimal movement since 2021-04-14, 1888 days at 0.03, as of 2026-06-15. arc-rules@v1

Foresight · where to check next

Cisco SecurePalo AltoAtlassianApache Log4j2MicrosoftUbiquiti Inc1687

This record is one instance of CWE-20, improper input validation. The index holds 13347 prior instances of this class, 73 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

Sources disagree here.

Severity score
Cisco6.8 MEDIUMreceipt
NVD7.5 HIGHreceipt
Scoring standard
CiscoCVSS v3.0receipt
NVDCVSS v3.1receipt
What it costs
CiscoComplete availability loss, with impact beyond the vulnerable componentreceipt
NVDComplete availability lossreceipt

Both shown, dated. We don't pick winners. disagreement-rules@v1

Running Cisco Adaptive Security Appliance (ASA)…? Check your version

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Harm, if it fires from the vector and the weakness

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Reachnetwork-reachable · no privileges required · no user interaction · high attack complexityreceipt
ImpactComplete availability loss, with impact beyond the vulnerable componentreceipt
Scored fromCVSS v3.0 · the CNA's vectorreceipt
Weakness classCWE-20 Improper Input Validationreceipt
Published consequencesCWE-20: Availability: DoS: Crash, Exit, or Restart, DoS: Resource Consumption (CPU), DoS: Resource Consumption (Memory); Confidentiality: Read Memory, Read Files or Directories…[email protected]

CISA KEV & Federal Remediation Deadline from the record and CISA

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

Fixed in9.4.4.34; 9.8.4; 9.9.2.50receipt
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 CNA6.8 MEDIUMreceipt
CVSS, NVD7.5 HIGHreceipt
Exploit probability0.029 · top 14% of all CVEsreceipt
Blast breadth2 products across 1 vendorderived
Assigned byciscoreceipt
Recorded changes17 · last 19 Sep 2026derived

Affected & Fixed Versions as published

Affected productCisco Adaptive Security Appliance (ASA) Softwarereceipt
Published rangescisco adaptive security appliance software < 9.4.4.34; cisco adaptive security appliance software >= 9.5 < 9.6.4.25; cisco adaptive security appliance software >= 9.7 < 9.8.4; cisco adaptive security appliance software >= 9.9 < 9.9.2.50receipt
Show all 7 published ranges
cisco adaptive security appliance software < 9.4.4.34
cisco adaptive security appliance software >= 9.5 < 9.6.4.25
cisco adaptive security appliance software >= 9.7 < 9.8.4
cisco adaptive security appliance software >= 9.9 < 9.9.2.50
cisco adaptive security appliance software >= 9.10 < 9.10.1.17
cisco secure firewall threat defense >= 6.0.0 < 6.2.3.12
cisco secure firewall threat defense >= 6.3.0 < 6.3.0.3
Fixed in9.4.4.34; 9.8.4; 9.9.2.50receipt

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 Adaptive Security Appliance (…CWE-20 improper input validationAdjacent componentsscope changeAvailability lossA:Hexploits CWE-20scope changedata compromise

What it is stated by the CNA

A vulnerability in the TCP proxy functionality for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to restart unexpectedly, resulting in a denial of service (DoS) condition. The vulnerability is due to an error in TCP-based packet inspection, which could cause the TCP packet to have an invalid Layer 2 (L2)-formatted header. An attacker could exploit this vulnerability by sending a crafted TCP packet sequence to the targeted device. A successful exploit could allow the attacker to cause a DoS condition. receipt

NVD's analysis a second authority

severity
7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
weakness
CWE-20
affected versions
cisco adaptive security appliance software < 9.4.4.34; cisco adaptive security appliance software >= 9.5 < 9.6.4.25; cisco adaptive security appliance software >= 9.7 < 9.8.4; and 4 more, listed in full below

The CNA scored it 6.8 and NVD 7.5. Both are shown because both were published; we do not pick one.

check it yourself tools.cisco.com securityfocus.com receipt

Movement the material steps

14 Apr 20210.00976
7 Mar 20230.00179 · scoring model v2023.03.01
17 Mar 20250.002 · scoring model v2025.03.14
15 Jun 20260.029 · scoring model v2026.06.15
Show all 17 observations
14 Apr 20210.00976
6 Jan 20220.04237
4 Feb 20220.04499
1 Apr 20220.01055
7 Mar 20230.00179
24 Mar 20230.00130
8 May 20230.00095
8 Jul 20230.00130
23 Sep 20240.00106
17 Dec 20240.00090
12 Mar 20250.00094
17 Mar 20250.002
19 Mar 20250.0025
29 Mar 20250.00432
30 Mar 20250.0025
12 Dec 20250.00211
15 Jun 20260.029

17 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 0.029Published2019-05-03Index as of2026-06-15

The record had been public for 7 years, 1 month when this index was last written.

Published 2019-05-03 receipt · Index as of 2026-06-15 derived

The pattern, elsewhere

This record is one instance of CWE-20, improper input validation. The index holds 13347 prior instances of this class, 73 KEV-listed. The nearest of its KEV-listed records are drawn beside this. [email protected]

CVE-2025-20393 · Cisco Secure Emailmatches 6 of 9KEV listed · 2025receipt
CVE-2024-3400 · Palo Alto Networks PAN-OSmatches 5 of 9KEV listed · 2024receipt
CVE-2023-22515 · Atlassian Confluence Data Centermatches 5 of 9KEV listed · 2023receipt
CVE-2021-44228 · Apache Log4j2matches 5 of 9KEV listed · 2021receipt
CVE-2017-0148 · Microsoft Corporation Windows SMBmatches 5 of 9KEV listed · 2017receipt
CVE-2026-34910 · Ubiquiti Inc UniFi OS Servermatches 5 of 9KEV listed · 2026receipt

"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

13347 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 adaptive security appliance

Of the 14 records in this family, this is the only one holding a stated fix version: 9.4.4.34; 9.8.4; 9.9.2.50.

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.

Browse the index from here

These are index-wide views, not findings about CVE-2019-1687.

What usually comes next

Everything above needs no account. What is below is work: assembling it, scoping it to your estate, watching it, and handing it to someone else.

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