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Fix GH-21673: password_verify() failed to verify bcrypt passwords containing null bytes #21675

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Fix GH-21673: password_verify() failed to verify bcrypt passwords containing null bytes #21675

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6f14bee
initial fix
LamentXU123 Apr 8, 2026
512fcdb
Update NEWS
LamentXU123 Apr 8, 2026
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2 changes: 2 additions & 0 deletions NEWS
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Original file line number Diff line number Diff line change
Expand Up @@ -138,6 +138,8 @@ PHP NEWS
while COW violation flag is still set). (alexandre-daubois)
. Added form feed (\f) in the default trimmed characters of trim(), rtrim()
and ltrim(). (Weilin Du)
. Fixed bug GH-21673 Reject NUL bytes in bcrypt passwords passed to
password_verify(). (Weilin Du)
. Invalid mode values now throw in array_filter() instead of being silently
defaulted to 0. (Jorg Sowa)
. Fixed bug GH-21058 (error_log() crashes with message_type 3 and
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6 changes: 6 additions & 0 deletions ext/standard/password.c
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Expand Up @@ -153,6 +153,12 @@ static bool php_password_bcrypt_needs_rehash(const zend_string *hash, zend_array

static bool php_password_bcrypt_verify(const zend_string *password, const zend_string *hash) {
int status = 0;

/* password_hash() already rejects NUL bytes for bcrypt inputs. */
if (memchr(ZSTR_VAL(password), '\0', ZSTR_LEN(password))) {
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@devnexen devnexen Apr 8, 2026

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nit: zend_str_has_nul_bytes(password)

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@devnexen devnexen Apr 8, 2026 •
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or what can be done is modifying password argument handling in password_hash/verify possibly.

return false;
}

zend_string *ret = php_crypt(ZSTR_VAL(password), (int)ZSTR_LEN(password), ZSTR_VAL(hash), (int)ZSTR_LEN(hash), 1);

if (!ret) {
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14 changes: 14 additions & 0 deletions ext/standard/tests/password/password_bcrypt_null_verify.phpt
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@@ -0,0 +1,14 @@
--TEST--
password_verify() rejects bcrypt passwords containing null bytes
--FILE--
<?php
$hash = password_hash("foo", PASSWORD_BCRYPT);

var_dump(password_verify("foo", $hash));
var_dump(password_verify("foo\0bar", $hash));
var_dump(password_verify("\0foo", $hash));
?>
--EXPECT--
bool(true)
bool(false)
bool(false)
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