CVE-2011-3621Network attack vector

Reverse proxy security issue

Published Jan 22, 2020 · Updated Aug 6, 2024

Reverse proxy issue in FluxBB before 1.4.7 allows remote attackers to affect confidentiality, integrity, and availability when the setting is enabled. The vendor record identifies mishandled reverse proxying but does not disclose the specific code locus or untrusted operation. Exploitation requires a deployment behind a reverse proxy with FORUM_BEHIND_REVERSE_PROXY enabled; the published scoring indicates network, unauthenticated impact across data disclosure, modification, and service availability.

CVSS severity9.8
Critical
EPSS probability1.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Reverse proxy issue in FluxBB before 1.4.7 allows remote attackers to affect confidentiality, integrity, and availability when the setting is enabled. The vendor record identifies mishandled reverse proxying but does not disclose the specific code locus or untrusted operation. Exploitation requires a deployment behind a reverse proxy with FORUM_BEHIND_REVERSE_PROXY enabled; the published scoring indicates network, unauthenticated impact across data disclosure, modification, and service availability.

The record

CVE
CVE-2011-3621
Published
Jan 22, 2020
Updated
Aug 6, 2024
Vendor
FluxBB
Product
FluxBB
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 22, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=before 1.4.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FluxBB · FluxBBversion=before 1.4.7

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NVDAV:N/AC:L/Au:N/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo