CVE-2020-8984Network attack vector

Client IP spoofing via trusted forwarded header

Published Mar 24, 2020 · Updated Aug 4, 2024

Origin validation error in ZendTo before 5.22-2 Beta allows remote attackers to spoof client IP addresses through HTTP headers. lib/NSSDropbox.php trusted the client-controlled X-Forwarded-For value when deriving the requester address instead of restricting forwarded headers to proxied deployments. No authentication is required, but the affected path matters only when forwarded address data is used; spoofing misattributes IP-based logs and security decisions.

CVSS severity7.5
High
EPSS probability0.49%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Origin validation error in ZendTo before 5.22-2 Beta allows remote attackers to spoof client IP addresses through HTTP headers. lib/NSSDropbox.php trusted the client-controlled X-Forwarded-For value when deriving the requester address instead of restricting forwarded headers to proxied deployments. No authentication is required, but the affected path matters only when forwarded address data is used; spoofing misattributes IP-based logs and security decisions.

The record

CVE
CVE-2020-8984
Published
Mar 24, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-346, T1036
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 24, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

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-346Origin Validation Error
T1036Masquerading

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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