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CVE-2021-34698

24
FAUCET Score

CVE-2021-34698 is a denial-of-service vulnerability in the proxy service of Cisco AsyncOS for Cisco Web Security Appliance (WSA) models S170, S190, S380, S390, S680, S690, and S690X. An unauthenticated, remote attacker can exploit this flaw by establishing numerous HTTPS connections, leading to memory exhaustion and a DoS condition requiring manual intervention for recovery. With a CVSS score of 7.5 (High), this vulnerability is easily exploitable over the network with low attack complexity and no user interaction, resulting in high availability impact. Currently, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 12.0, < 12.0.3-005CPE matchmatch criteria
cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:*
>= 12.5, < 12.5.2-007CPE matchmatch criteria
cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:*
>= 14.0, < 14.0.1-014CPE matchmatch criteria
cpe:2.3:o:cisco:asyncos:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.6HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
4.0
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.39%
Probability of exploitation in next 30 days
EPSS Percentile
69.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0139 is in the 50th percentile among its peer group of 51,485 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

ciscovendor investigatingvia nvd_reference
View patch

References

tools.cisco.com / security/center/content/CiscoSecurityAdvisory/cisco-sa-wsa-dos-fmHdKswk
Vendor Advisory