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HighKEV

CVE-2026-20349 — Cisco Secure Firewall Adaptive Security Appliance and Secure Firewall Threat Defense Software Remote Access SSL VPN Denial of Service Vulnerability

CVE-2026-20349 · Secure Firewall ASA · CVSS 8.6 · KEV

In brief

Severity · CVSS
High8.6CVSS 3.1, High
EPSS
1%
CISA KEV
Known exploited, listed since 11 Aug 2026
Vendor
Cisco
Published · Modified
·
Last verified

Summary

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.

Weakness: CWE-244

Title, description and the vendor's statements are quoted from the CVE record; a vendor's advisory is summarised in Patcharo's words, with a link.

Affected and fixed versions

Per product and release branch, as the vendor's CVE record and official advisory state them. A fixed release is shown only when a document names it: the vendor's, or CERT-FR's for Check Point, with its source.

12 branches with a published fixed release · 3 branches without a precise fixed release

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software

Source: cisco-sa-asaftd-vpn-dos-dzv4mQFFCVE-2026-20349

  1. 9.24
    Affected versions9.24.1, 9.24.1.5, 9.24.1.9, 9.24.1.11
    5 releases listed9.24.1, 9.24.1.5, 9.24.1.9, 9.24.1.11, 9.24.1.155
    First fixed release9.24.1.26
  2. 9.23
    Affected versions9.23.1, 9.23.1.3, 9.23.1.7, 9.23.1.13
    9 releases listed9.23.1, 9.23.1.3, 9.23.1.7, 9.23.1.13, 9.23.1.19, 9.23.1.22, 9.23.1.26, 9.23.1.32, 9.23.1.195
    First fixed release9.23.1.47
  3. 9.22
    Affected versions9.22.1.1, 9.22.1.2, 9.22.1.3, 9.22.1.6
    13 releases listed9.22.1.1, 9.22.1.2, 9.22.1.3, 9.22.1.6, 9.22.2, 9.22.2.4, 9.22.2.9, 9.22.2.13, 9.22.2.14, 9.22.2.20, 9.22.2.32, 9.22.3, 9.22.3.5
    First fixed release9.22.3.26
  4. 9.20
    Affected versions9.20.1, 9.20.1.5, 9.20.2, 9.20.2.10
    23 releases listed9.20.1, 9.20.1.5, 9.20.2, 9.20.2.10, 9.20.2.21, 9.20.2.22, 9.20.3, 9.20.3.4, 9.20.3.7, 9.20.3.9, 9.20.3.10, 9.20.3.13, 9.20.3.16, 9.20.3.20, 9.20.4, 9.20.4.7, 9.20.4.10, 9.20.4.14, 9.20.4.19, 9.20.4.22, 9.20.4.28, 9.20.4.30, 9.20.4.34
    First fixed release9.20.4.49
  5. 9.19
    Affected versions9.19.1, 9.19.1.5, 9.19.1.9, 9.19.1.12
    13 releases listed9.19.1, 9.19.1.5, 9.19.1.9, 9.19.1.12, 9.19.1.18, 9.19.1.22, 9.19.1.24, 9.19.1.27, 9.19.1.28, 9.19.1.31, 9.19.1.37, 9.19.1.38, 9.19.1.42
    First fixed releaseNot published in the sources followed
  6. 9.18
    Affected versions9.18.1, 9.18.1.3, 9.18.2, 9.18.2.5
    32 releases listed9.18.1, 9.18.1.3, 9.18.2, 9.18.2.5, 9.18.2.7, 9.18.2.8, 9.18.3, 9.18.3.39, 9.18.3.46, 9.18.3.53, 9.18.3.55, 9.18.3.56, 9.18.4, 9.18.4.5, 9.18.4.8, 9.18.4.22, 9.18.4.24, 9.18.4.29, 9.18.4.34, 9.18.4.40, 9.18.4.47, 9.18.4.50, 9.18.4.52, 9.18.4.53, 9.18.4.57, 9.18.4.66, 9.18.4.67, 9.18.4.68, 9.18.4.71, 9.18.4.76, 9.18.4.82, 9.18.4.135
    First fixed release9.18.4.94
  7. 9.16
    Affected versions9.16.1, 9.16.1.28, 9.16.2, 9.16.2.3
    37 releases listed9.16.1, 9.16.1.28, 9.16.2, 9.16.2.3, 9.16.2.7, 9.16.2.11, 9.16.2.13, 9.16.2.14, 9.16.3, 9.16.3.3, 9.16.3.14, 9.16.3.15, 9.16.3.19, 9.16.3.23, 9.16.4, 9.16.4.9, 9.16.4.14, 9.16.4.18, 9.16.4.19, 9.16.4.27, 9.16.4.38, 9.16.4.39, 9.16.4.42, 9.16.4.48, 9.16.4.55, 9.16.4.57, 9.16.4.61, 9.16.4.62, 9.16.4.67, 9.16.4.70, 9.16.4.71, 9.16.4.76, 9.16.4.82, 9.16.4.84, 9.16.4.85, 9.16.4.89, 9.16.4.92
    First fixed release9.16.4.103

Cisco Secure Firewall Threat Defense (FTD) Software

Source: cisco-sa-asaftd-vpn-dos-dzv4mQFFCVE-2026-20349

  1. 10.1
    Affected versions< 10.1.0
    First fixed release10.1
  2. 10.0
    Affected versions10.0, 10.0.2
    First fixed releaseThe vendor sources Patcharo follows contradict each other10.0.2: stated as fixed by cisco-sa-asaftd-vpn-dos-dzv4mQFF, listed as affected by the CVE record
  3. 7.7
    Affected versions7.7, 7.7.10, 7.7.10.1, 7.7.11
    First fixed release7.7.13
  4. 7.6
    Affected versions7.6, 7.6.1, 7.6.2, 7.6.2.1
    5 releases listed7.6, 7.6.1, 7.6.2, 7.6.2.1, 7.6.4
    First fixed release7.6.6
  5. 7.4
    Affected versions7.4, 7.4.1, 7.4.1.1, 7.4.2
    11 releases listed7.4, 7.4.1, 7.4.1.1, 7.4.2, 7.4.2.1, 7.4.2.2, 7.4.2.3, 7.4.2.4, 7.4.3, 7.4.4, 7.4.7
    First fixed release7.4.8
  6. 7.3
    Affected versions7.3, 7.3.1, 7.3.1.1, 7.3.1.2
    First fixed releaseNot published in the sources followed
  7. 7.2
    Affected versions7.2, 7.2.0.1, 7.2.1, 7.2.2
    18 releases listed7.2, 7.2.0.1, 7.2.1, 7.2.2, 7.2.3, 7.2.4, 7.2.4.1, 7.2.5, 7.2.5.1, 7.2.5.2, 7.2.6, 7.2.7, 7.2.8, 7.2.8.1, 7.2.9, 7.2.10, 7.2.10.2, 7.2.11
    First fixed release7.2.12
  8. 7.0
    Affected versions7.0, 7.0.0.1, 7.0.1, 7.0.1.1
    17 releases listed7.0, 7.0.0.1, 7.0.1, 7.0.1.1, 7.0.2, 7.0.2.1, 7.0.3, 7.0.4, 7.0.5, 7.0.6, 7.0.6.1, 7.0.6.2, 7.0.6.3, 7.0.7, 7.0.8, 7.0.8.1, 7.0.9
    First fixed release7.0.10

Remediation

Fix available

Vendor fix

  • Secure Firewall Adaptive Security Appliance (ASA) Software 9.249.24.1.26
  • Secure Firewall Adaptive Security Appliance (ASA) Software 9.239.23.1.47
  • Secure Firewall Adaptive Security Appliance (ASA) Software 9.229.22.3.26
  • Secure Firewall Adaptive Security Appliance (ASA) Software 9.209.20.4.49
  • Secure Firewall Adaptive Security Appliance (ASA) Software 9.189.18.4.94
  • Secure Firewall Adaptive Security Appliance (ASA) Software 9.169.16.4.103
  • Secure Firewall Threat Defense (FTD) Software 10.110.1
  • Secure Firewall Threat Defense (FTD) Software 7.77.7.13
  • Secure Firewall Threat Defense (FTD) Software 7.67.6.6
  • Secure Firewall Threat Defense (FTD) Software 7.47.4.8
  • Secure Firewall Threat Defense (FTD) Software 7.27.2.12
  • Secure Firewall Threat Defense (FTD) Software 7.07.0.10

Upgrade to a fixed release listed above for your branch, or to a later fixed release the vendor explicitly supports.

Cisco has released updates that fix this vulnerability; its advisory lists them.

SourceCisco Security Advisory cisco-sa-asaftd-vpn-dos-dzv4mQFF

Workarounds (vendor)

Cisco states in its advisory that no workaround is available.

SourceCisco Security Advisory cisco-sa-asaftd-vpn-dos-dzv4mQFF

CISA KEV required action

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes).

Full CISA action

Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

CISA due date:

SourceCISA KEV

CERT-FR recommendation

Refer to the vendor's security bulletin to obtain patches (see Documentation section).

SourceCERTFR-2026-AVI-1010

Last verified 1 Oct 2026 at 09:31 UTC

Known exploitation

Added to CISA KEV on 11 Aug 2026

Federal remediation due date: 14 Aug 2026

The CISA required action is shown under Remediation.

1% probability of exploitation in the next 30 days (percentile 62%).

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

CERT-FR

1 document of the French national CERT (ANSSI) references this CVE.

Advisory (AVI)CERTFR-2026-AVI-1010Published 12 Aug 2026

Vulnerability in Cisco products

Remote denial of service

Summary

A vulnerability has been discovered in Cisco products. It allows an attacker to cause a remote denial of service. Cisco indicates that the vulnerability CVE-2026-20349 is being actively exploited.

Recommendation

Refer to the vendor's security bulletin to obtain patches (see Documentation section).

Official document on cert.ssi.gouv.frread by Patcharo 28 Sept 2026 at 20:03 UTCMachine translation of the French text published by CERT-FR; a text whose translation did not pass Patcharo's checks stays in French. Identifiers, versions and links are copied unchanged.

Timeline

  1. Added to CISA KEV
  2. Published by the source
  3. CISA remediation due date
  4. Source record last modified
  5. EPSS score computed
  6. Last verified by Patcharo

Official sources

References

Cisco · CISA Known Exploited Vulnerabilities · NVD · FIRST EPSS · Cisco Security Advisory cisco-sa-asaftd-vpn-dos-dzv4mQFF

How Patcharo reads this

Affected and fixed releases come from the vendor's structured statements and are matched against exact versions; CVSS from NVD, exploitation from CISA KEV and the vendor's own advisory, probability from FIRST EPSS. Missing data stays Unknown and never becomes Not affected.

Read the methodologyRead the guide: Cisco Secure Firewall release trains: Threat Defense, Management Center and ASA versions explained

Related vulnerabilities

Other records affecting the same products, newest first.

  • CVE-2025-20362Cisco Secure Firewall Adaptive Security (ASA) Appliance and Secure Firewall Threat Defense (FTD) Missing Authorization VulnerabilityHighKEV
  • CVE-2025-20333Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow VulnerabilityCriticalKEV
  • CVE-2024-20481Cisco ASA and FTD Denial-of-Service VulnerabilityMediumKEV
  • CVE-2024-20359Cisco ASA and FTD Privilege Escalation VulnerabilityMediumKEV
  • CVE-2024-20353Cisco ASA and FTD Denial of Service VulnerabilityHighKEV

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