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CVE-2020-3516

17
FAUCET Score

CVE-2020-3516 is a medium-severity vulnerability affecting Cisco IOS XE Software, specifically within its web server authentication. An authenticated, remote attacker can exploit insufficient input validation by entering unexpected characters during authentication, leading to a denial-of-service condition where the web server crashes. Recovery requires manual intervention to disable and re-enable the web server. While no public exploit code or active exploitation has been observed, and community discussion is minimal, the vulnerability could still impact system availability.

Impacted Technologies

VendorProductVersion(s)CPE
< 16.9.6CPE matchmatch criteria
cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:*
>= 16.12.0, < 16.12.2CPE matchmatch criteria
cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:*
>= 17.1.0, < 17.1.1CPE matchmatch criteria
cpe:2.3:o:cisco:ios_xe:*:*:*:*:*:*:*:*
17.2.1CPE matchmatch criteria
cpe:2.3:o:cisco:ios_xe:17.2.1:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

4.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.67%
Probability of exploitation in next 30 days
EPSS Percentile
74.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0167 is in the 87th percentile among its peer group of 21,977 CVEs.

Social Chatter

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

tools.cisco.com / security/center/content/CiscoSecurityAdvisory/cisco-sa-WEB-UI-exNFmcPO
Vendor Advisory