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apply deterministic refactor of regex patterns to counter ReDoS #1671

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apply deterministic refactor of regex patterns to counter ReDoS #1671

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21fec97
apply deterministic refactor of regex patterns to counter ReDoS
fiammybe Nov 7, 2025
51f16d0
Update htdocs/plugins/preloads/adsense.php
fiammybe Nov 18, 2025
0630d12
Merge branch 'ImpressCMS:2.0.x' into deterministic-regex-refactor
fiammybe Dec 5, 2025
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36 changes: 32 additions & 4 deletions htdocs/plugins/preloads/adsense.php
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Original file line number Diff line number Diff line change
Expand Up @@ -40,8 +40,7 @@ function eventFinishCoreBoot() {
* @return void
*/
public function eventAfterPreviewTarea($array) {
$array[0] = preg_replace_callback(array("/\[adsense](.*)\[\/adsense\]/sU"),
'icms_sanitizeAdsenses_callback', $array[0]);
$array[0] = self::replaceTagDeterministic($array[0], 'adsense', 'icms_sanitizeAdsenses_callback');
}

/**
Expand All @@ -60,8 +59,7 @@ public function eventAfterPreviewTarea($array) {
* @return void
*/
public function eventAfterDisplayTarea($array) {
$array[0] = preg_replace_callback(array("/\[adsense](.*)\[\/adsense\]/sU"),
'icms_sanitizeAdsenses_callback', $array[0]);
$array[0] = self::replaceTagDeterministic($array[0], 'adsense', 'icms_sanitizeAdsenses_callback');
}

/**
Expand All @@ -81,4 +79,34 @@ public function eventStartOutputInit() {
$icmsTpl->assign('icmsAdsenses', $adsenses_array);
}
}

/**
* Deterministically replace [tag]...[/tag] occurrences by invoking a preg-style callback.
* Builds a $matches array like preg_replace_callback would: [0] full match, [1] inner.
*
* @param string $text
* @param string $tag e.g. 'adsense'
* @param callable $callback e.g. 'icms_sanitizeAdsenses_callback'
* @return string
*/
private static function replaceTagDeterministic(string $text, string $tag, $callback): string
{
$open = '[' . $tag . ']';
$close = '[/' . $tag . ']';
$pos = 0;
while (($start = strpos($text, $open, $pos)) !== false) {
$innerStart = $start + strlen($open);
$end = strpos($text, $close, $innerStart);
if ($end === false) {
break;
}
$inner = substr($text, $innerStart, $end - $innerStart);
$full = substr($text, $start, ($end + strlen($close)) - $start);
$replacement = call_user_func($callback, array($full, $inner));
$text = substr_replace($text, $replacement, $start, ($end + strlen($close)) - $start);
$pos = $start + strlen($replacement);
}
return $text;
}
}

36 changes: 32 additions & 4 deletions htdocs/plugins/preloads/customtag.php
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Original file line number Diff line number Diff line change
Expand Up @@ -39,8 +39,7 @@ function eventFinishCoreBoot() {
* @return void
*/
function eventBeforePreviewTarea($array) {
$array[0] = preg_replace_callback(array('/\[customtag](.*)\[\/customtag\]/sU'),
"icms_sanitizeCustomtags_callback", $array[0]);
$array[0] = self::replaceTagDeterministic($array[0], 'customtag', 'icms_sanitizeCustomtags_callback');
}

/**
Expand All @@ -59,8 +58,7 @@ function eventBeforePreviewTarea($array) {
* @return void
*/
function eventBeforeDisplayTarea($array) {
$array[0] = preg_replace_callback(array('/\[customtag](.*)\[\/customtag\]/sU'),
"icms_sanitizeCustomtags_callback", $array[0]);
$array[0] = self::replaceTagDeterministic($array[0], 'customtag', 'icms_sanitizeCustomtags_callback');
}

/**
Expand All @@ -80,4 +78,34 @@ function eventStartOutputInit() {
$icmsTpl->assign("icmsCustomtags", $customtags_array);
}
}

/**
* Deterministically replace [tag]...[/tag] occurrences by invoking a preg-style callback.
* Builds a $matches array like preg_replace_callback would: [0] full match, [1] inner.
*
* @param string $text
* @param string $tag e.g. 'customtag'
* @param callable $callback e.g. 'icms_sanitizeCustomtags_callback'
* @return string
*/
private static function replaceTagDeterministic(string $text, string $tag, $callback): string
{
$open = '[' . $tag . ']';
$close = '[/' . $tag . ']';
$pos = 0;
while (($start = strpos($text, $open, $pos)) !== false) {
$innerStart = $start + strlen($open);
$end = strpos($text, $close, $innerStart);
if ($end === false) {
break;
}
$inner = substr($text, $innerStart, $end - $innerStart);
$full = substr($text, $start, ($end + strlen($close)) - $start);
$replacement = call_user_func($callback, array($full, $inner));
$text = substr($text, 0, $start) . $replacement . substr($text, $end + strlen($close));
$pos = $start + strlen($replacement);
}
return $text;
}

}