A vulnerability in the External Database Access feature of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated,… (CVE-2026-20242)
A critical vulnerability exists in the External Database Access feature of Cisco Secure Firewall Management Center (FMC) Software that allows an unauthenticated remote attacker to execute arbitrary commands as root. The flaw arises from insecure deserialization of a user-supplied Java byte stream from a host configured in the external database access list. Exploitation requires control over a host in this access list and involves sending a crafted serialized Java byte stream to a specific TCP port. The vulnerability has a CVSS score of 9.8, indicating severe impact. The attack surface is reduced if the FMC management interface is not exposed to the public internet. No patch or remediation information is currently provided.
AI Analysis
Technical Summary
CVE-2026-20242 is a critical vulnerability in Cisco Secure Firewall Management Center (FMC) Software's External Database Access feature. It stems from insecure deserialization of Java byte streams supplied by hosts in the external database access list. An attacker controlling such a host can send a crafted serialized Java byte stream to a designated TCP port on the FMC device, leading to arbitrary command execution with root privileges. The vulnerability requires no prior authentication and has a CVSS 3.1 base score of 9.8, reflecting high exploitability and impact. The risk is mitigated if the FMC management interface is not publicly accessible. No official patch or fix details are currently available.
Potential Impact
Successful exploitation allows an unauthenticated remote attacker, controlling a host in the external database access list, to execute arbitrary commands as root on the affected FMC device. This results in full system compromise, including confidentiality, integrity, and availability impacts.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Mitigation includes restricting control of hosts in the external database access list and limiting FMC management interface exposure to the public internet to reduce attack surface.
A vulnerability in the External Database Access feature of Cisco Secure Firewall Management Center (FMC) Software could allow an unauthenticated,… (CVE-2026-20242)
Description
A critical vulnerability exists in the External Database Access feature of Cisco Secure Firewall Management Center (FMC) Software that allows an unauthenticated remote attacker to execute arbitrary commands as root. The flaw arises from insecure deserialization of a user-supplied Java byte stream from a host configured in the external database access list. Exploitation requires control over a host in this access list and involves sending a crafted serialized Java byte stream to a specific TCP port. The vulnerability has a CVSS score of 9.8, indicating severe impact. The attack surface is reduced if the FMC management interface is not exposed to the public internet. No patch or remediation information is currently provided.
CVSS v3.1
Score 9.8critical
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-20242 is a critical vulnerability in Cisco Secure Firewall Management Center (FMC) Software's External Database Access feature. It stems from insecure deserialization of Java byte streams supplied by hosts in the external database access list. An attacker controlling such a host can send a crafted serialized Java byte stream to a designated TCP port on the FMC device, leading to arbitrary command execution with root privileges. The vulnerability requires no prior authentication and has a CVSS 3.1 base score of 9.8, reflecting high exploitability and impact. The risk is mitigated if the FMC management interface is not publicly accessible. No official patch or fix details are currently available.
Potential Impact
Successful exploitation allows an unauthenticated remote attacker, controlling a host in the external database access list, to execute arbitrary commands as root on the affected FMC device. This results in full system compromise, including confidentiality, integrity, and availability impacts.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Mitigation includes restricting control of hosts in the external database access list and limiting FMC management interface exposure to the public internet to reduce attack surface.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-mgpv-rwhr-9mx2
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-20242"]
- Database Specific Severity
- CRITICAL
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aab49aa55bf5e2cf599290b
Added to database: 09/17/2026, 02:00:10 UTC
Last enriched: 09/17/2026, 02:41:23 UTC
Last updated: 09/17/2026, 05:01:37 UTC
Views: 2
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