CVE-2024-4577Known exploitationPublic exploitNetwork attack vector

Unauthenticated code execution via Best-Fit argument injection

Published Jun 9, 2024 · Updated Oct 21, 2025

Argument injection in PHP-CGI 8.1 before 8.1.29, 8.2 before 8.2.20, and 8.3 before 8.3.8 allows remote attackers to execute PHP code. In sapi/cgi/cgi_main.c, the query-string guard checks for an ASCII hyphen before Windows Best-Fit conversion maps a soft hyphen into that option prefix. An unauthenticated HTTP request reaches this path when Apache invokes PHP in CGI mode on Windows with an affected code page; injected options can disclose script source or run server-side code.

CVSS severity9.8
Critical
EPSS probability99.99%
Next 30 days · Nov 1, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Argument injection in PHP-CGI 8.1 before 8.1.29, 8.2 before 8.2.20, and 8.3 before 8.3.8 allows remote attackers to execute PHP code. In sapi/cgi/cgi_main.c, the query-string guard checks for an ASCII hyphen before Windows Best-Fit conversion maps a soft hyphen into that option prefix. An unauthenticated HTTP request reaches this path when Apache invokes PHP in CGI mode on Windows with an affected code page; injected options can disclose script source or run server-side code.

The record

CVE
CVE-2024-4577
Published
Jun 9, 2024
Updated
Oct 21, 2025
Vendor
PHP Development Team
Product
PHP
Classifications
CWE-78, CWE-20, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 9, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2025Record 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=8.1.0 <8.1.29
  2. Affected versionversion=8.1.* <8.1.29
  3. Affected versionversion=8.2.0 <8.2.20
  4. Affected versionversion=8.2.* <8.2.20
  5. Affected versionversion=8.3.0 <8.3.8
  6. Affected versionversion=8.3.* <8.3.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PHP Development Team · PHPversion=8.1.0 <8.1.29; version=8.1.* <8.1.29; version=8.2.0 <8.2.20; version=8.2.* <8.2.20; version=8.3.0 <8.3.8; version=8.3.* <8.3.8

Published CVSS scores

9.8PHP GroupCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsShadowserver observations through Sep 28, 2026. Gaps indicate unavailable data.
Sep 22, 2026Sep 28, 2026
View daily counts
Reporting dayUnique IPs
Sep 22, 20262
Sep 23, 20263
Sep 24, 20263
Sep 25, 2026Unavailable
Sep 26, 20263
Sep 27, 20261
Sep 28, 2026Unavailable
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
CWE-20Improper Input Validation
T1190Exploit Public-Facing Application

Public exploit references

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

Reported exploitation

Technologies

Your stack

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Your stack

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