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CVE-2018-15453

28
FAUCET Score

CVE-2018-15453 is a denial-of-service vulnerability in Cisco AsyncOS Software for Cisco Email Security Appliance (ESA) affecting the S/MIME Decryption and Verification or Public Key Harvesting features. An unauthenticated, remote attacker can exploit improper input validation in S/MIME-signed emails to corrupt system memory, causing the filtering process to crash and restart. This vulnerability has a CVSS score of 8.6 (High) due to its network attack vector, low attack complexity, and high impact on availability, potentially leading to a permanent DoS condition requiring manual intervention. There is no public exploit code available (Metasploit, Nuclei, ExploitDB), and it is not listed in CISA's KEV catalog, indicating it is not actively exploited. However, it has garnered some community discussion and media coverage, suggesting awareness within the cybersecurity community.

Impacted Technologies

VendorProductVersion(s)CPE
11.0.1-401CPE matchmatch criteria
cpe:2.3:o:cisco:email_security_appliance_firmware:11.0.1-401:*:*:*:*:*:*:*
11.1.0-131CPE matchmatch criteria
cpe:2.3:o:cisco:email_security_appliance_firmware:11.1.0-131:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

8.6HIGH

CVSS:3.0/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
3.0

Exploit Intelligence

EPSS Score
2.29%
Probability of exploitation in next 30 days
EPSS Percentile
81.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0229 is in the 67th percentile among its peer group of 51,553 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

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-20190109-esa-dos
Vendor Advisory
securityfocus.com / bid/106511
Third Party AdvisoryVDB Entry