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-rw-r--r--system/libraries/Email.php58
1 files changed, 51 insertions, 7 deletions
diff --git a/system/libraries/Email.php b/system/libraries/Email.php
index bfff8953b..1483f2203 100644
--- a/system/libraries/Email.php
+++ b/system/libraries/Email.php
@@ -450,7 +450,6 @@ class CI_Email {
$this->_headers = array();
$this->_debug_msg = array();
- $this->set_header('User-Agent', $this->useragent);
$this->set_header('Date', $this->_set_date());
if ($clear_attachments !== FALSE)
@@ -1824,6 +1823,33 @@ class CI_Email {
// --------------------------------------------------------------------
/**
+ * Validate email for shell
+ *
+ * Applies stricter, shell-safe validation to email addresses.
+ * Introduced to prevent RCE via sendmail's -f option.
+ *
+ * @see https://github.com/bcit-ci/CodeIgniter/issues/4963
+ * @see https://gist.github.com/Zenexer/40d02da5e07f151adeaeeaa11af9ab36
+ * @license https://creativecommons.org/publicdomain/zero/1.0/ CC0 1.0, Public Domain
+ *
+ * Credits for the base concept go to Paul Buonopane <paul@namepros.com>
+ *
+ * @param string $email
+ * @return bool
+ */
+ protected function _validate_email_for_shell(&$email)
+ {
+ if (function_exists('idn_to_ascii') && $atpos = strpos($email, '@'))
+ {
+ $email = self::substr($email, 0, ++$atpos).idn_to_ascii(self::substr($email, $atpos));
+ }
+
+ return (filter_var($email, FILTER_VALIDATE_EMAIL) === $email && preg_match('#\A[a-z0-9._+-]+@[a-z0-9.-]{1,253}\z#i', $email));
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
* Send using mail()
*
* @return bool
@@ -1835,9 +1861,18 @@ class CI_Email {
$this->_recipients = implode(', ', $this->_recipients);
}
+ // _validate_email_for_shell() below accepts by reference,
+ // so this needs to be assigned to a variable
+ $from = $this->clean_email($this->_headers['Return-Path']);
+
+ if ( ! $this->_validate_email_for_shell($from))
+ {
+ return mail($this->_recipients, $this->_subject, $this->_finalbody, $this->_header_str);
+ }
+
// most documentation of sendmail using the "-f" flag lacks a space after it, however
// we've encountered servers that seem to require it to be in place.
- return mail($this->_recipients, $this->_subject, $this->_finalbody, $this->_header_str, '-f '.$this->clean_email($this->_headers['Return-Path']));
+ return mail($this->_recipients, $this->_subject, $this->_finalbody, $this->_header_str, '-f '.$from);
}
// --------------------------------------------------------------------
@@ -1849,13 +1884,22 @@ class CI_Email {
*/
protected function _send_with_sendmail()
{
+ // _validate_email_for_shell() below accepts by reference,
+ // so this needs to be assigned to a variable
+ $from = $this->clean_email($this->_headers['From']);
+ if ($this->_validate_email_for_shell($from))
+ {
+ $from = '-f '.$from;
+ }
+ else
+ {
+ $from = '';
+ }
+
// is popen() enabled?
- if ( ! function_usable('popen')
- OR FALSE === ($fp = @popen(
- $this->mailpath.' -oi -f '.escapeshellarg($this->clean_email($this->_headers['From'])).' -t'
- , 'w'))
- ) // server probably has popen disabled, so nothing we can do to get a verbose error.
+ if ( ! function_usable('popen') OR FALSE === ($fp = @popen($this->mailpath.' -oi '.$from.' -t', 'w')))
{
+ // server probably has popen disabled, so nothing we can do to get a verbose error.
return FALSE;
}