Fix path_info pointer underflow in CGI fix_pathinfo handling - #23411
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iliaal wants to merge 1 commit into
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Fix path_info pointer underflow in CGI fix_pathinfo handling#23411iliaal wants to merge 1 commit into
iliaal wants to merge 1 commit into
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When the PATH_INFO supplied by the webserver is shorter than the suffix stripped from SCRIPT_FILENAME, computing env_path_info + pilen - slen underflows and the subsequent path_info[0] = 0 writes out of bounds before the start of the string. The FPM side of this same loop was hardened by commit ab061f9 (CVE-2019-11043) but sapi/cgi was never given the equivalent guard. Mirror it: only derive path_info when pilen exceeds slen, and skip the ORIG_*/SCRIPT_NAME juggling when there is no extracted path.
NickSdot
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Aug 22, 2026
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| @unlink($f); | ||
| @rmdir($d); |
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| @unlink($f); | |
| @rmdir($d); | |
| ?> | |
| --CLEAN-- | |
| <?php | |
| $d = __DIR__ . '/fix_pathinfo_underflow'; | |
| @unlink($d . '/info.php'); | |
| @rmdir($d); |
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cgi.fix_pathinfo derived PATH_INFO as env_path_info + pilen - slen even when PATH_INFO was shorter than the suffix stripped from SCRIPT_FILENAME, which under-runs the pointer. FPM received this guard in ab061f9; CGI did not.