CVE-2020-28873Network attack vector

Unauthenticated denial of service via long password

Published Mar 17, 2021 · Updated Jul 9, 2026

Denial of service in the FluxBB 1.5.11 login form allows remote attackers to exhaust server CPU and memory with a long password. The login path hashes an attacker-controlled password without first limiting its length, causing an extremely long value to consume excessive processor time and memory. No authentication or user interaction is required, and the reported consequence is service interruption rather than data disclosure or modification.

CVSS severity7.5
High
EPSS probability0.86%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in the FluxBB 1.5.11 login form allows remote attackers to exhaust server CPU and memory with a long password. The login path hashes an attacker-controlled password without first limiting its length, causing an extremely long value to consume excessive processor time and memory. No authentication or user interaction is required, and the reported consequence is service interruption rather than data disclosure or modification.

The record

CVE
CVE-2020-28873
Published
Mar 17, 2021
Updated
Jul 9, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-916, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 17, 2021CVE publishedPublication date reported by the CVE source.
  2. Jul 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-916Use of Password Hash With Insufficient Computational Effort
T1499.003Application Exhaustion Flood

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

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Your stack

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