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CVE-2021-43406

27
FAUCET Score

CVE-2021-43406 is a high-severity vulnerability affecting FusionPBX versions prior to 4.5.30, where the 'fax_post_size' parameter is not properly constrained, allowing for the injection of risky characters. This flaw carries a CVSS score of 8.8, indicating a high potential for impact on confidentiality, integrity, and availability, and can be exploited remotely with low attack complexity and requiring only low privileges. While the vulnerability is significant, there is currently no known active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or community discussion surrounding it.

Impacted Technologies

VendorProductVersion(s)CPE
< 4.5.30CPE matchmatch criteria
cpe:2.3:a:fusionpbx:fusionpbx:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

8.8HIGH

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.94%
Probability of exploitation in next 30 days
EPSS Percentile
57.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0094 is in the 53rd percentile among its peer group of 17,844 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.3 Bluesky, 0.1 Mastodon, and 0.2 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

github.com / fusionpbx/fusionpbx/commit/0377b2152c0e59c8f35297f9a9b6ee335a62d963
PatchThird Party Advisory