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CVE-2020-3191

27
FAUCET Score

CVE-2020-3191 is a high-severity denial-of-service vulnerability affecting Cisco Adaptive Security Appliance (ASA) and Firepower Threat Defense (FTD) Software. It stems from improper length validation in IPv6 DNS packet processing, allowing an unauthenticated, remote attacker to cause a device reload by sending a crafted DNS query over IPv6. The vulnerability has a CVSS score of 8.6, indicating a high impact with no user interaction required. While no public exploit code or active exploitation is confirmed, it has garnered some community discussion and media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 6.2.3, < 6.2.3.16CPE matchmatch criteria
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
>= 6.3.0, < 6.3.0.6CPE matchmatch criteria
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
>= 6.4.0, < 6.4.0.6CPE matchmatch criteria
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
9.4\(1\)CPE matchmatch criteria
cpe:2.3:o:cisco:asa_5505_firmware:9.4\(1\):*:*:*:*:*:*:*
96.4\(0.42\)CPE matchmatch criteria
cpe:2.3:o:cisco:asa_5505_firmware:96.4\(0.42\):*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.6HIGH

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
4.0
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.82%
Probability of exploitation in next 30 days
EPSS Percentile
76.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0182 is in the 59th percentile among its peer group of 51,551 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

ciscovendor investigatingvia nvd_reference
View patch

References

tools.cisco.com / security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ipv6-67pA658k
Vendor Advisory