How severe is CVE-2019-1817?

CVE-2019-1817 has a CVSS 3.x base score of 7.5, rated high 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 high.

Is CVE-2019-1817 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-1817?

CVE-2019-1817 primarily affects Cisco Web Security Appliance. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-1817?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2019-1817 published?

CVE-2019-1817 was published on 2019-05-03 and last updated on 2026-06-17.

CVE-2019-1817

CVE-2019-1817 is a high-severity vulnerability in Cisco Web Security Appliance with a CVSS 3.x base score of 7.5. 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-20.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Cisco Web Security Appliance
Published: 2019-05-03
Last modified: 2026-06-17

Description

A vulnerability in the web proxy functionality of Cisco AsyncOS Software for Cisco Web Security Appliance could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper validation of HTTP and HTTPS requests. An attacker could exploit this vulnerability by sending a malformed HTTP or HTTPS request to an affected device. An exploit could allow the attacker to cause a restart of the web proxy process, resulting in a temporary DoS condition.

Frequently asked questions

What is CVE-2019-1817?: A vulnerability in the web proxy functionality of Cisco AsyncOS Software for Cisco Web Security Appliance could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to improper validation of HTTP and HTTPS requests. An attacker could exploit this vulnerability by sending a malformed HTTP or HTTPS request to an affected device. An exploit could allow the attacker to cause a restart of the web proxy process, resulting in a temporary DoS condition.
How severe is CVE-2019-1817?: CVE-2019-1817 has a CVSS 3.x base score of 7.5, rated high 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 high.
Is CVE-2019-1817 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-1817?: CVE-2019-1817 primarily affects Cisco Web Security Appliance. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-1817?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2019-1817 published?: CVE-2019-1817 was published on 2019-05-03 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190501-wsa-dos

Affected products (4)

cpe:2.3:a:cisco:web_security_appliance:11.5.1-fcs-115:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:11.5.1-fcs-124:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:11.5.1-fcs-125:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:11.7.0-fcs-334:*:*:*:*:*:*:*

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