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Reject malformed Unicode escape sequences #1176

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Merged
nikic merged 1 commit into from
Oct 5, 2026
+36 −1
Merged

Reject malformed Unicode escape sequences #1176

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5 changes: 4 additions & 1 deletion lib/PhpParser/Node/Scalar/String_.php
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Original file line number Diff line number Diff line change
Expand Up @@ -116,7 +116,7 @@ public static function parseEscapeSequences(string $str, ?string $quote, bool $p

$extra = '';
if ($parseUnicodeEscape) {
$extra = '|u\{([0-9a-fA-F]+)\}';
$extra = '|u\{([0-9a-fA-F]+)\}|u\{';
}

return preg_replace_callback(
Expand All @@ -131,6 +131,9 @@ function ($matches) {
return chr(hexdec(substr($str, 1)));
}
if ('u' === $str[0]) {
if (!isset($matches[2])) {
throw new Error('Invalid UTF-8 codepoint escape sequence');
}
// PHP 8.6 warns when hexdec() produces a float.
$dec = @hexdec($matches[2]);
// If it overflowed to float, treat as INT_MAX, it will throw an error anyway.
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32 changes: 32 additions & 0 deletions test/code/parser/scalar/unicodeEscape.test
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Expand Up @@ -86,3 +86,35 @@ Invalid UTF-8 codepoint escape sequence: Codepoint too large on line 2
"\u{110000}";
-----
Invalid UTF-8 codepoint escape sequence: Codepoint too large on line 2
-----
<?php
"\u{zz}";
-----
Invalid UTF-8 codepoint escape sequence on line 2
-----
<?php
"\u{}";
-----
Invalid UTF-8 codepoint escape sequence on line 2
-----
<?php
"\u{4z}";
-----
Invalid UTF-8 codepoint escape sequence on line 2
-----
<?php
"\u{41";
-----
Invalid UTF-8 codepoint escape sequence on line 2

@nikic nikic Oct 4, 2026

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Probably worth testing "\u{" as well, as the minimal invalid sequence?

On the other hand, I'd drop the tests with variables below -- at least it's not obvious to me what extra coverage they are adding.

@ydah ydah Oct 5, 2026

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Thank you. Added a test for \u{ and removed the cases with variables as suggested.

-----
<?php
"\u{";
-----
Invalid UTF-8 codepoint escape sequence on line 2
-----
<?php
<<<STR
\u{}
STR;
-----
Invalid UTF-8 codepoint escape sequence on line 4
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