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CVE-2021-27520

41
FAUCET Score

CVE-2021-27520 is a reflected cross-site scripting (XSS) vulnerability in FUDForum version 3.1.0, allowing remote attackers to inject malicious JavaScript code through the "author" parameter in index.php. This medium-severity vulnerability has a CVSS score of 6.1, indicating that it can be exploited over the network with low attack complexity, requiring user interaction to achieve partial confidentiality and integrity impacts. While there is no evidence of active exploitation in the wild (KEV and Hot List are inactive), public exploit code is available via ExploitDB and Nuclei templates. Community discussion and media coverage for this CVE are minimal.

Impacted Technologies

VendorProductVersion(s)CPE
3.1.0CPE matchmatch criteria
cpe:2.3:a:fudforum:fudforum:3.1.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.1MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
6.40%
Probability of exploitation in next 30 days
EPSS Percentile
92.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
Nuclei: CVE-2021-27520 · Mar 5, 2023
ExploitDB: EDB-49943 · Jun 3, 2021
This CVE's current EPSS score of 0.0640 is in the 97th percentile among its peer group of 26,219 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 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

packetstormsecurity.com / files/162942/FUDForum-3.1.0-Cross-Site-Scripting.html
ExploitThird Party AdvisoryVDB Entry
github.com / fudforum/FUDforum/issues/2
ExploitIssue TrackingPatchThird Party Advisory