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GHSA-v66g-p9x6-v98p
No affected components available
Summary
One of the sample scripts in PhpSpreadsheet is susceptible to a cross-site scripting (XSS) vulnerability due to improper handling of input where a number is expected leading to formula injection.
Details
The following code in 45_Quadratic_equation_solver.php concatenates the user supplied parameters directly into spreadsheet formulas. This allows an attacker to take control over the formula and output unsanitized data into the page, resulting in JavaScript execution.
$discriminantFormula = '=POWER(' . $_POST['B'] . ',2) - (4 * ' . $_POST['A'] . ' * ' . $_POST['C'] . ')';
$discriminant = Calculation::getInstance()->calculateFormula($discriminantFormula);
$r1Formula = '=IMDIV(IMSUM(-' . $_POST['B'] . ',IMSQRT(' . $discriminant . ')),2 * ' . $_POST['A'] . ')';
$r2Formula = '=IF(' . $discriminant . '=0,"Only one root",IMDIV(IMSUB(-' . $_POST['B'] . ',IMSQRT(' . $discriminant . ')),2 * ' . $_POST['A'] . '))';
PoC
- Access
45_Quadratic_equation_solver.phpin a browser - Enter any valid values for for
bandc, and enter the following fora
1) & ("1)),1)&char(60)&char(105)&char(109)&char(103)&char(32)&char(115)&char(114)&char(99)&char(61)&char(120)&char(32)&char(111)&char(110)&char(101)&char(114)&char(114)&char(111)&char(114)&char(61)&char(97)&char(108)&char(101)&char(114)&char(116)&char(40)&char(41)&char(62)&POWER(((1") &n("1")&(1
- Press submit and observe that JavaScript is executed.
Impact
The impact of this vulnerability on the project is expected to be relatively low since these are sample files that should not be included when the library is used properly (e.g., through composer). However, at least two instances of popular WordPress plugins have unintentionally exposed this file by including the entire git repository. Since these files also serve as reference points for developers using the library, addressing this issue can enhance security for users.
A solution to fix the vulnerability is proposed below, and a request for a CVE assignment has been made to facilitate responsible disclosure of the security issue to the affected WordPress plugins.
Remediation
A quick and easy solution to prevent this attack is to force the parameters to be numerical values:
if (isset($_POST['submit'])) {
$_POST['A'] = floatval($_POST['A']);
$_POST['B'] = floatval($_POST['B']);
$_POST['C'] = floatval($_POST['C']);
if ($_POST['A'] == 0) {
Thank you for your time!
The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The vulnerability can affect other systems as well, not just the initial system. There is a low impact on the confidentiality of the information. There is a low impact on the integrity of the data.
Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.
The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.
We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.
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