How severe is CVE-2020-3557?

CVE-2020-3557 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2020-3557 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-3557?

CVE-2020-3557 affects Cisco Secure Firewall Management Center. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-3557?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-3557 published?

CVE-2020-3557 was published on 2020-10-21 and last updated on 2026-06-17.

CVE-2020-3557

CVE-2020-3557 is a medium-severity vulnerability in Cisco Secure Firewall Management Center with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-295.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 1% (49th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-295
Affected product: Cisco Secure Firewall Management Center
Published: 2020-10-21
Last modified: 2026-06-17

Description

A vulnerability in the host input API daemon of Cisco Firepower Management Center (FMC) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper certificate validation. An attacker could exploit this vulnerability by sending a crafted data stream to the host input daemon of the affected device. A successful exploit could allow the attacker to cause the host input daemon to restart. The attacker could use repeated attacks to cause the daemon to continuously reload, creating a DoS condition for the API.

Frequently asked questions

What is CVE-2020-3557?: A vulnerability in the host input API daemon of Cisco Firepower Management Center (FMC) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper certificate validation. An attacker could exploit this vulnerability by sending a crafted data stream to the host input daemon of the affected device. A successful exploit could allow the attacker to cause the host input daemon to restart. The attacker could use repeated attacks to cause the daemon to continuously reload, creating a DoS condition for the API.
How severe is CVE-2020-3557?: CVE-2020-3557 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2020-3557 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (49th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-3557?: CVE-2020-3557 affects Cisco Secure Firewall Management Center. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-3557?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-3557 published?: CVE-2020-3557 was published on 2020-10-21 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-fmc-dos-3WymYWKh

Affected products (1)

cpe:2.3:a:cisco:secure_firewall_management_center:*:*:*:*:*:*:*:*

More vulnerabilities in Cisco Secure Firewall Management Center

CVE-2026-20131 — Critical (CVSS 10.0): A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software could…
CVE-2025-20265 — Critical (CVSS 10.0): A vulnerability in the RADIUS subsystem implementation of Cisco Secure Firewall Management Center (FMC) Software could…
CVE-2024-20424 — Critical (CVSS 9.9): A vulnerability in the web-based management interface of Cisco Secure Firewall Management Center (FMC) Software,…
CVE-2023-20048 — Critical (CVSS 9.9): A vulnerability in the web services interface of Cisco Firepower Management Center (FMC) Software could allow an…
CVE-2019-16028 — Critical (CVSS 9.8): A vulnerability in the web-based management interface of Cisco Firepower Management Center (FMC) could allow an…
CVE-2020-3318 — Critical (CVSS 9.8): Multiple vulnerabilities in Cisco Firepower Management Center (FMC) Software and Cisco Firepower User Agent Software…

All CVEs affecting Cisco Secure Firewall Management Center →

Other CWE-295 (Improper Certificate Validation) vulnerabilities

CVE-2026-4370 — Critical (CVSS 10.0): A vulnerability was identified in Juju from version 3.2.0 until 3.6.19 and from version 4.0 until 4.0.4, where the…
CVE-2026-30836 — Critical (CVSS 10.0): Step CA is an online certificate authority for secure, automated certificate management for DevOps. Versions 0.30.0-rc6…
CVE-2025-68121 — Critical (CVSS 10.0): During session resumption in crypto/tls, if the underlying Config has its ClientCAs or RootCAs fields mutated between…
CVE-2022-20703 — Critical (CVSS 10.0): Multiple vulnerabilities in Cisco Small Business RV160, RV260, RV340, and RV345 Series Routers could allow an attacker…
CVE-2021-1471 — Critical (CVSS 9.9): Multiple vulnerabilities in Cisco Jabber for Windows, Cisco Jabber for MacOS, and Cisco Jabber for mobile platforms…
CVE-2026-20184 — Critical (CVSS 9.8): A vulnerability in the integration of single sign-on (SSO) with Control Hub in Cisco Webex Services could have allowed…

Browse all CWE-295 (Improper Certificate Validation) vulnerabilities →