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CVE-2026-20349

Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability

CVSS 3.1 High 8.6Known exploited (CISA KEV)

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Description

A vulnerability in the Remote Access SSL VPN service for Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause the device to reload unexpectedly, resulting in a denial of service (DoS) condition.  This vulnerability is due to insufficient error checking when processing HTTP requests. An attacker could exploit this vulnerability by sending a crafted HTTP request to the Remote Access SSL VPN service on an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

Official description from the CVE record, published by cisco. Copyright © 1999-2026 The MITRE Corporation. See /security/cve/legal for the CVE license. View the record on cve.org

Key data

CVSS 3.1 High 8.6

Score published by cisco in the CVE record.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

  • Attack vector: Network

    The vulnerable component can be reached over a network, possibly from the Internet.

  • Attack complexity: Low

    No special conditions are needed. The attack can be repeated at will.

  • Privileges required: None

    No account or privileges are needed.

  • User interaction: None

    No action from any user is needed.

  • Scope: Changed

    The impact can reach other components beyond the vulnerable one.

  • Confidentiality impact: None

    No effect on the secrecy of data.

  • Integrity impact: None

    No effect on the trustworthiness of data.

  • Availability impact: High

    Serious or total effect on availability.

CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at first.org/cvss.

EPSS

Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days.
Score
0.01010 (1.0% probability)
Percentile
63.4%
Scores of
Nov 10, 2026
Model
v2026.06.15

CISA Known Exploited Vulnerabilities

This CVE is listed in the CISA KEV catalog.
Name in the catalog
Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Heap Inspection Vulnerability
Added to the catalog
Aug 11, 2026
Federal due date
Aug 14, 2026

CISA assessment as of Aug 11, 2026

Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA.
Exploitation
Recorded by CISA as active
Automatable
yes
Technical impact
partial

Weakness (CWE)

CWE catalog version 5.0.
CWE names: Copyright © 2006-2026, The MITRE Corporation. See /security/cve/legal for the CWE license.
  • CWE-244Improper Clearing of Heap Memory Before Release

Affected products

Products listed in the CVE record, as the CNA published them.

  • Cisco Secure Firewall Adaptive Security Appliance (ASA) Software

    • affected: 9.16.1
    • affected: 9.16.1.28
    • affected: 9.16.2
    • affected: 9.16.2.3
    • affected: 9.16.2.7
    • affected: 9.16.2.11
    • affected: 9.16.2.13
    • affected: 9.16.2.14
    • affected: 9.16.3.3
    • affected: 9.16.3
    • affected: 9.16.3.14
    • affected: 9.18.1
    • affected: 9.16.3.15
    • affected: 9.18.1.3
    • affected: 9.18.2
    • affected: 9.16.3.19
    • affected: 9.16.3.23
    • affected: 9.18.2.5
    • affected: 9.16.4
    • affected: 9.18.2.7
    • affected: 9.19.1
    • affected: 9.16.4.9
    • affected: 9.18.2.8
    • affected: 9.16.4.14
    • affected: 9.18.3
    • and 107 more

  • Cisco Secure Firewall Threat Defense (FTD) Software

    • affected: 7.0.0
    • affected: 7.0.0.1
    • affected: 7.0.1
    • affected: 7.0.1.1
    • affected: 7.0.2
    • affected: 7.2.0
    • affected: 7.0.2.1
    • affected: 7.0.3
    • affected: 7.2.0.1
    • affected: 7.0.4
    • affected: 7.2.1
    • affected: 7.0.5
    • affected: 7.3.0
    • affected: 7.2.2
    • affected: 7.2.3
    • affected: 7.3.1
    • affected: 7.2.4
    • affected: 7.0.6
    • affected: 7.2.5
    • affected: 7.2.4.1
    • affected: 7.3.1.1
    • affected: 7.4.0
    • affected: 7.0.6.1
    • affected: 7.2.5.1
    • affected: 7.4.1
    • and 36 more

References

Links listed in the CVE record. They lead to other sites, which CubePath does not control.

Timeline

  1. ID reserved
  2. Added to CISA KEV
  3. Record published
  4. Record last updated

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About CubePath

CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection.
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Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 19:09 UTC. Sources and licenses