CVE-2026-55584Public exploitNetwork attack vector

Unauthenticated system-information disclosure via spoofed client headers

Published Aug 28, 2026 · Updated Aug 28, 2026

Authentication bypass in phpSysInfo before 3.4.6 allows remote attackers to read exposed system information through spoofed HTTP headers. The PSI_ALLOWED check in read_config.php accepts X-Forwarded-For or Client-IP as the client address before REMOTE_ADDR, letting supplied allowlisted values impersonate trusted clients. Exploitation requires PSI_ALLOWED to be configured and exposes host, kernel, processor, memory, filesystem, and network-interface details.

CVSS severity7.5
High
EPSS probability2.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in phpSysInfo before 3.4.6 allows remote attackers to read exposed system information through spoofed HTTP headers. The PSI_ALLOWED check in read_config.php accepts X-Forwarded-For or Client-IP as the client address before REMOTE_ADDR, letting supplied allowlisted values impersonate trusted clients. Exploitation requires PSI_ALLOWED to be configured and exposes host, kernel, processor, memory, filesystem, and network-interface details.

The record

CVE
CVE-2026-55584
Published
Aug 28, 2026
Updated
Aug 28, 2026
Vendor
phpSysInfo
Product
phpSysInfo
Classifications
CWE-290, T1016, T1082
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 28, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 28, 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?

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

  1. Affected versionversion=< 3.4.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

phpSysInfo · phpSysInfoversion=< 3.4.6

Published CVSS scores

7.5GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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.

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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 exploitPublished

Weakness, pattern, technique

CWE-290Authentication Bypass by Spoofing
T1016System Network Configuration Discovery
T1082System Information Discovery

Public exploit references

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Technologies

Your stack

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Your stack

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