Every CVE Search/ Get API key

CVE-2019-1981

Cisco Firepower Threat Defense Software NULL Character Obfuscation Detection Bypass Vulnerability

5.8 Medium

A vulnerability in the normalization functionality of Cisco Firepower Threat Defense Software, Cisco FirePOWER Services Software for ASA, and Cisco Firepower Management Center Software could allow an unauthenticated, remote attacker to bypass filtering protections. The vulnerability is due to insufficient normalization of a text-based payload. An attacker could exploit this vulnerability by sending traffic that contains specifically obfuscated payloads through an affected device. An exploit could allow the attacker to bypass filtering and deliver malicious payloads to protected systems that would otherwise be blocked.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
Low
Availability
None

Exploit likelihood

1.04%Up 0.5 points since Apr 14, 2021
90%50%10%1%

What each source reports

CVE List Score used 5.8

Cisco Firepower Threat Defense Software NULL Character Obfuscation Detection Bypass Vulnerability

A vulnerability in the normalization functionality of Cisco Firepower Threat Defense Software, Cisco FirePOWER Services Software for ASA, and Cisco Firepower Management Center Software could allow an unauthenticated, remote attacker to bypass filtering protections. The vulnerability is due to insufficient normalization of a text-based payload. An attacker could exploit this vulnerability by sending traffic that contains specifically obfuscated payloads through an affected device. An exploit could allow the attacker to bypass filtering and deliver malicious payloads to protected systems that would otherwise be blocked.

Record
CVE-2019-1981
CVSS 3.0
5.8 MediumCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Weakness
CWE-264
Updated
2026-11-02
EUVDEUVD-2019-10538 5.8

A vulnerability in the normalization functionality of Cisco Firepower Threat Defense Software, Cisco FirePOWER Services Software for ASA, and Cisco Firepower Management Center Software could allow an unauthenticated, remote attacker to bypass filtering protections. The vulnerability is due to insufficient normalization of a text-based payload. An attacker could exploit this vulnerability by sending traffic that contains specifically obfuscated payloads through an affected device. An exploit could allow the attacker to bypass filtering and deliver malicious payloads to protected systems that would otherwise be blocked.

Record
EUVD-2019-10538
CVSS 3.0
5.8 MediumCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Updated
2026-11-03
GitHub AdvisoriesGHSA-55w6-hghf-mfpw 5.8

A vulnerability in the normalization functionality of Cisco Firepower Threat Defense Software,...

A vulnerability in the normalization functionality of Cisco Firepower Threat Defense Software, Cisco FirePOWER Services Software for ASA, and Cisco Firepower Management Center Software could allow an unauthenticated, remote attacker to bypass filtering protections. The vulnerability is due to insufficient normalization of a text-based payload. An attacker could exploit this vulnerability by sending traffic that contains specifically obfuscated payloads through an affected device. An exploit could allow the attacker to bypass filtering and deliver malicious payloads to protected systems that would otherwise be blocked.

Record
GHSA-55w6-hghf-mfpw
CVSS 3.1
5.8 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Weakness
CWE-20
Updated
2026-11-02
NVD 5.8

A vulnerability in the normalization functionality of Cisco Firepower Threat Defense Software, Cisco FirePOWER Services Software for ASA, and Cisco Firepower Management Center Software could allow an unauthenticated, remote attacker to bypass filtering protections. The vulnerability is due to insufficient normalization of a text-based payload. An attacker could exploit this vulnerability by sending traffic that contains specifically obfuscated payloads through an affected device. An exploit could allow the attacker to bypass filtering and deliver malicious payloads to protected systems that would otherwise be blocked.

Record
CVE-2019-1981
CVSS 3.1
5.8 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
CVSS 3.0
5.8 MediumCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:N/I:P/A:N
Weakness
CWE-264, CWE-20
Updated
2026-11-02

Affected products

History

History
RecordedChangedSources
aliases, publishedEUVD
first indexedCVE List, GitHub Advisories, NVD

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2019-1981 is a medium vulnerability (CVSS 5.8) in Cisco Firepower Threat Defense Software, published November 5, 2019. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.04%, the 64th percentile. No source names a fixed version.

References

MoveEnter Open