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CVE-2021-1611

26
FAUCET Score

CVE-2021-1611 is a denial-of-service vulnerability in Cisco IOS XE Wireless Controller Software for Catalyst 9800 Family Wireless Controllers and Embedded Wireless on Catalyst 9000 Series Switches. It stems from improper processing of malformed Ethernet over GRE (EoGRE) packets. An unauthenticated, remote attacker can exploit this by sending malicious packets, causing the device to reload and resulting in a high-severity DoS (CVSS 8.6). There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 17.3.1CPE matchmatch criteria
cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:*

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
1.33%
Probability of exploitation in next 30 days
EPSS Percentile
68.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0133 is in the 48th percentile among its peer group of 51,506 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

Patch Available

Vendor Patches (1)

ciscopatch availablevia nvd_reference
View patch

References

tools.cisco.com / security/center/content/CiscoSecurityAdvisory/cisco-sa-ewlc-gre-6u4ELzAT
PatchVendor Advisory