CVE-2021-34698

Cisco Web Security Appliance Proxy Service Denial of Service Vulnerability

HIGH

7.5

CVSS Score

Published: October 6, 2021 at 07:46 PM UTC

Updated: June 17, 2026 at 03:56 AM UTC

9 products affected across 1 vendorAsyncosWeb Security Appliance S170Web Security Appliance S690X

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Severity

HIGH7.5

Exploit prediction

EPSS 1%

SSVC

No known exploit

Description

A vulnerability in the proxy service of Cisco AsyncOS for Cisco Web Security Appliance (WSA) could allow an unauthenticated, remote attacker to exhaust system memory and cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper memory management in the proxy service of an affected device. An attacker could exploit this vulnerability by establishing a large number of HTTPS connections to the affected device. A successful exploit could allow the attacker to cause the system to stop processing new connections, which could result in a DoS condition. Note: Manual intervention may be required to recover from this situation.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Asyncos · Cisco

95%

12.0 ≤ v < 12.0.3-00512.5 ≤ v < 12.5.2-00714.0 ≤ v < 14.0.1-014

Affected range stops below 12.0.3-005, so it looks safe — our inference, not a vendor statement

Affected range stops below 12.5.2-007, so it looks safe — our inference, not a vendor statement

Affected range stops below 14.0.1-014, so it looks safe — our inference, not a vendor statement

cisco-web-security-appliance-s170 (environment) · cisco-web-security-appliance-s190 (environment) · cisco-web-security-appliance-s380 (environment) · cisco-web-security-appliance-s390 (environment) · cisco-web-security-appliance-s680 (environment) · cisco-web-security-appliance-s690 (environment) · cisco-web-security-appliance-s690x (environment)

Web Security Appliance · Cisco

60%

All versions

Web Security Appliance S170 · Ciscodevice

80%

All versions

Web Security Appliance S190 · Ciscodevice

80%

All versions

Web Security Appliance S380 · Ciscodevice

80%

All versions