8.6

CVE-2026-20039: cisco adaptive_security_appliance_software Heap Inspection

CVSS: 8.6v3.1HighAnalyzed
Published 04-03-2026Last modified 05-03-2026
Open JSON

Vulnerability summary

CVE-2026-20039 is a high (CVSS 8.6) Heap Inspection vulnerability in cisco adaptive_security_appliance_software. EPSS estimates a 0.37% chance of exploitation in the next 30 days, higher than 29.9% of scored vulnerabilities.

Overall risk
34/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.6/10
010
High · v3.1 (CVE.org)
EPSS score
0.37%
0%100%
Low · +0.01 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Timeline

  1. 04-03-2026
    PublishedVulnerability first disclosed.
  2. 05-03-2026
    Last modifiedVulnerability information updated.

Description

A vulnerability in the VPN web server of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to ineffective memory management of the VPN web server. An attacker could exploit this vulnerability by sending a large number of crafted HTTP requests to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

CVSS metrics

2 scores · 2 sources · 1 version

EPSS trend

Probability

0.37%

Chance of exploitation in the next 30 days

Percentile

30%

Versus all other CVEs

30-day change

+0.01 pp

From 0.36% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.37%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Cisco4 products
  • adaptive_security_appliance_software≥ 9.12.1, < 9.16.4.84 | ≥ 9.17.1, < 9.18.4.57 | ≥ 9.19.1, < 9.20.3.16 | ≥ 9.22.1.1, < 9.22.2.4 | ≥ 9.23.1, < 9.23.1.3
  • cisco secure firewall adaptive security appliance (asa) software9.12.3 | 9.12.1 | 9.12.2 | 9.12.4 | 9.12.3.2 | 9.12.3.7 | 9.12.2.5 | 9.12.3.12 | 9.12.1.3 | 9.12.2.4 | 9.12.1.2 | 9.12.2.9 | 9.12.3.9 | 9.12.2.1 | 9.12.4.2 | 9.12.4.4 | 9.12.4.7 | 9.12.4.8 | 9.12.4.10 | 9.12.4.13 | 9.12.4.18 | 9.12.4.24 | 9.16.1 | 9.12.4.26 | 9.16.1.28 | 9.12.4.29 | 9.16.2 | 9.12.4.30 | 9.16.2.3 | 9.12.4.35 | 9.16.2.7 | 9.12.4.37 | 9.17.1 | 9.16.2.11 | 9.16.2.13 | 9.12.4.39 | 9.12.4.38 | 9.16.2.14 | 9.17.1.7 | 9.12.4.40 | 9.16.3.3 | 9.16.3 | 9.16.3.14 | 9.17.1.9 | 9.12.4.41 | 9.17.1.10 | 9.18.1 | 9.12.4.47 | 9.16.3.15 | 9.18.1.3 | 9.17.1.11 | 9.12.4.48 | 9.18.2 | 9.16.3.19 | 9.17.1.13 | 9.12.4.50 | 9.17.1.15 | 9.12.4.52 | 9.16.3.23 | 9.18.2.5 | 9.16.4 | 9.12.4.54 | 9.17.1.20 | 9.18.2.7 | 9.19.1 | 9.16.4.9 | 9.12.4.55 | 9.18.2.8 | 9.16.4.14 | 9.18.3 | 9.19.1.5 | 9.12.4.56 | 9.17.1.30 | 9.19.1.9 | 9.18.3.39 | 9.16.4.19 | 9.12.4.58 | 9.19.1.12 | 9.18.3.46 | 9.16.4.27 | 9.19.1.18 | 9.18.3.53 | 9.18.3.55 | 9.16.4.38 | 9.17.1.33 | 9.12.4.62 | 9.16.4.39 | 9.18.3.56 | 9.20.1 | 9.16.4.42 | 9.19.1.22 | 9.18.4 | 9.20.1.5 | 9.18.4.5 | 9.19.1.24 | 9.16.4.48 | 9.18.4.8 | 9.20.2 | 9.19.1.27 | 9.12.4.65 | 9.16.4.55 | 9.18.4.22 | 9.20.2.10 | 9.16.4.57 | 9.19.1.28 | 9.17.1.39 | 9.12.4.67 | 9.18.4.24 | 9.20.2.21 | 9.16.4.61 | 9.19.1.31 | 9.18.4.29 | 9.20.2.22 | 9.16.4.62 | 9.18.4.34 | 9.20.3 | 9.16.4.67 | 9.16.4.70 | 9.18.4.40 | 9.23.1 | 9.22.1.1 | 9.16.4.71 | 9.20.3.4 | 9.18.4.47 | 9.20.3.7 | 9.17.1.45 | 9.19.1.37 | 9.17.1.46 | 9.16.4.76 | 9.20.3.9 | 9.19.1.38 | 9.18.4.50 | 9.22.1.3 | 9.20.3.10 | 9.22.1.2 | 9.18.4.52 | 9.20.3.13 | 9.22.1.6 | 9.18.4.53 | 9.16.4.82 | 9.22.2 | 9.19.1.42
  • cisco secure firewall threat defense (ftd) software6.4.0.1 | 6.4.0.2 | 6.4.0.5 | 6.4.0 | 6.4.0.3 | 6.4.0.4 | 6.4.0.6 | 6.4.0.7 | 6.4.0.8 | 6.4.0.9 | 6.4.0.10 | 6.4.0.11 | 6.4.0.12 | 7.0.0 | 7.0.0.1 | 7.0.1 | 7.1.0 | 6.4.0.13 | 7.0.1.1 | 6.4.0.14 | 7.1.0.1 | 7.0.2 | 6.4.0.15 | 7.2.0 | 7.0.2.1 | 7.0.3 | 7.1.0.2 | 7.2.0.1 | 7.0.4 | 7.2.1 | 7.0.5 | 6.4.0.16 | 7.3.0 | 7.2.2 | 7.2.3 | 7.3.1 | 7.1.0.3 | 7.2.4 | 7.0.6 | 7.2.5 | 7.2.4.1 | 7.3.1.1 | 7.4.0 | 6.4.0.17 | 7.0.6.1 | 7.2.5.1 | 7.4.1 | 7.2.6 | 7.0.6.2 | 7.4.1.1 | 6.4.0.18 | 7.2.7 | 7.2.5.2 | 7.3.1.2 | 7.2.8 | 7.6.0 | 7.4.2 | 7.2.8.1 | 7.0.6.3 | 7.4.2.1 | 7.2.9 | 7.0.7 | 7.7.0 | 7.4.2.2 | 7.4.2.3 | 7.0.8 | 7.0.8.1 | 7.4.2.4
  • secure_firewall_threat_defense≥ 6.4.0, < 7.0.9 | ≥ 7.1.0, < 7.2.10 | ≥ 7.3.0, < 7.4.3 | ≥ 7.6.0, < 7.6.1 | ≥ 7.7.0, < 7.7.10

1 vendor · 4 products

References

1 links