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CVE-2020-3555

19
FAUCET Score

CVE-2020-3555 describes a denial-of-service vulnerability in Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software. An unauthenticated, remote attacker can exploit a flaw in the SIP inspection process by sending a high rate of crafted SIP traffic, leading to a watchdog timeout and device reload. This vulnerability carries a CVSS score of 7.5 (High), indicating a network-based attack with low complexity and high impact on availability. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 9.6.4.43CPE matchmatch criteria
cpe:2.3:a:cisco:adaptive_security_appliance:*:*:*:*:*:*:*:*
<= 6.2.2CPE 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, < 6.4.0.10CPE matchmatch criteria
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
>= 6.5.0, < 6.5.0.5CPE matchmatch criteria
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.8MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.2
Impact Score
4.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.68%
Probability of exploitation in next 30 days
EPSS Percentile
74.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0168 is in the 57th percentile among its peer group of 51,553 CVEs.

Social Chatter

No social media mentions found for this CVE.

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

No media coverage found for this CVE.

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-sipdos-3DGvdjvg
Vendor Advisory