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 Exam Form Submission Code Projects

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

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. A public proof-of-concept exploit is available on GitHub, and the vulnerability has an EPSS score indicating probable exploitation likelihood.

Technical ContextAI

The vulnerability is a Reflected or Stored Cross-Site Scripting (CWE-79) flaw in a PHP-based application (cpe:2.3:a:code-projects:exam_form_submission:*:*:*:*:*:*:*:*). The root cause is inadequate input validation and output encoding of user-supplied data in the 'sname' parameter passed to /admin/update_s1.php. The PHP application fails to apply proper context-aware output encoding (HTML entity encoding, JavaScript escaping, or similar) before rendering the sname value in HTML responses. This allows attackers to inject arbitrary HTML and JavaScript payloads that execute with the privileges of the authenticated user viewing the page, potentially leading to session hijacking, credential theft, or administrative account compromise.

RemediationAI

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. If no patch is available, implement input validation by rejecting or encoding the 'sname' parameter using HTML entity encoding (e.g., htmlspecialchars() in PHP with ENT_QUOTES flag) before rendering it in HTML context. Additionally, apply output encoding to all user-supplied variables in the /admin/update_s1.php response, implement a Content Security Policy (CSP) header to restrict inline script execution, and restrict access to the /admin/ directory to trusted IP ranges via firewall or web server configuration. Consider implementing CSRF tokens and session-based protections to mitigate secondary attack vectors. Regular security audits of the application codebase are strongly recommended.