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CVE-2021-1236

20
FAUCET Score

CVE-2021-1236 describes a medium-severity vulnerability in the Snort application detection engine affecting multiple Cisco products. This flaw allows an unauthenticated, remote attacker to bypass security policies by sending crafted packets, potentially delivering malicious payloads to protected networks. The vulnerability has a CVSS score of 5.3, indicating low attack complexity and no user interaction required. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
< 17.4.1CPE matchmatch criteria
cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:*
< 6.5.0.5CPE matchmatch criteria
cpe:2.3:a:cisco:firepower_threat_defense:*:*:*:*:*:*:*:*
2.9.14.0CPE matchmatch criteria
cpe:2.3:a:cisco:secure_firewall_management_center:2.9.14.0:*:*:*:*:*:*:*
2.9.14.14CPE matchmatch criteria
cpe:2.3:a:cisco:secure_firewall_management_center:2.9.14.14:*:*:*:*:*:*:*
2.9.15CPE matchmatch criteria
cpe:2.3:a:cisco:secure_firewall_management_center:2.9.15:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

4.0MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
CHANGED
Confidentiality Impact
NONE
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
1.4
CvssVersion
3.0

Exploit Intelligence

EPSS Score
2.15%
Probability of exploitation in next 30 days
EPSS Percentile
80.2%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0215 is in the 69th percentile among its peer group of 23,723 CVEs.

Social Chatter

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

Media Mentions

No media coverage found for this CVE.

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

Remediation

Vendor Patches (1)

ciscovendor investigatingvia nvd_reference
View patch

References

lists.debian.org / debian-lts-announce/2023/02/msg00011.html
tools.cisco.com / security/center/content/CiscoSecurityAdvisory/cisco-sa-snort-app-bypass-cSBYCATq
Vendor Advisory
debian.org / security/2023/dsa-5354