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Fix GH-25089: Heap buffer over-read via crafted alias size in zip-based phar #25099

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Fix GH-25089: Heap buffer over-read via crafted alias size in zip-based phar #25099

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4569f86
Fix GH-25089: Heap buffer over-read via crafted alias size in zip-bas…
lazerg Oct 31, 2026
3262ce1
Wrap long lines in gh25089.phpt
lazerg Oct 31, 2026
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35 changes: 35 additions & 0 deletions ext/phar/tests/zip/gh25089.phpt
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Original file line number Diff line number Diff line change
@@ -0,0 +1,35 @@
--TEST--
GH-25089 (Heap buffer over-read via crafted alias size in zip-based phar)
--EXTENSIONS--
phar
zlib
--FILE--
<?php
$name = '.phar/alias.txt';
$alias = 'ABCD';
$data = gzdeflate($alias);
$crc = crc32($alias);
$claimed = 0x1000;

$local = "PK\x03\x04"
. pack('vvvvvVVVvv', 20, 0, 8, 0, 0,
$crc, strlen($data), $claimed, strlen($name), 0)
. $name . $data;
$central = "PK\x01\x02"
. pack('vvvvvvVVVvvvvvVV', 20, 20, 0, 8, 0, 0,
$crc, strlen($data), $claimed, strlen($name), 0, 0, 0, 0, 0, 0)
. $name;
$end = "PK\x05\x06"
. pack('vvvvVVv', 0, 0, 1, 1, strlen($central), strlen($local), 0);

file_put_contents(__DIR__ . '/gh25089.zip', $local . $central . $end);

$phar = new PharData(__DIR__ . '/gh25089.zip');
var_dump($phar->getAlias());
?>
--CLEAN--
<?php
@unlink(__DIR__ . '/gh25089.zip');
?>
--EXPECT--
string(4) "ABCD"
3 changes: 2 additions & 1 deletion ext/phar/zip.c
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Original file line number Diff line number Diff line change
Expand Up @@ -648,7 +648,6 @@ int phar_parse_zipfile(php_stream *fp, char *fname, size_t fname_len, char *alia
fp->readpos = 0;
/* the above lines should be for php < 5.2.6 after 5.3 filters are fixed */

mydata->alias_len = entry.uncompressed_filesize;
if (entry.flags & PHAR_ENT_COMPRESSED_GZ) {
filter = php_stream_filter_create("zlib.inflate", NULL, php_stream_is_persistent(fp));

Expand Down Expand Up @@ -735,6 +734,8 @@ int phar_parse_zipfile(php_stream *fp, char *fname, size_t fname_len, char *alia
}
}

mydata->alias_len = entry.uncompressed_filesize;

/* return to central directory parsing */
php_stream_seek(fp, restore_pos, SEEK_SET);
}
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