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From 42a11261b9dad2e48d70bdff7c53dd57a12db6f5 Mon Sep 17 00:00:00 2001
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From: AIMOTO Norihito <aimoto@osstech.co.jp>
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Date: Tue, 6 Jul 2021 22:57:24 +0200
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Subject: [PATCH] Prevent redirect to URLs that begin with '///'
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Visiting a logout URL like this:
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https://rp.example.co.jp/mellon/logout?ReturnTo=///fishing-site.example.com/logout.html
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would have redirected the user to fishing-site.example.com
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With the patch, this URL would be rejected.
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Fixes: CVE-2021-3639
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---
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auth_mellon_util.c | 10 ++++++++++
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1 file changed, 10 insertions(+)
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diff --git a/auth_mellon_util.c b/auth_mellon_util.c
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index 2f8c9c3..6a686db 100644
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--- a/auth_mellon_util.c
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+++ b/auth_mellon_util.c
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@@ -927,6 +927,10 @@ int am_check_url(request_rec *r, const char *url)
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{
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const char *i;
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+ if (url == NULL) {
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+ return HTTP_BAD_REQUEST;
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+ }
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+
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for (i = url; *i; i++) {
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if (*i >= 0 && *i < ' ') {
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/* Deny all control-characters. */
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@@ -943,6 +947,12 @@ int am_check_url(request_rec *r, const char *url)
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}
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}
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+ if (strstr(url, "///") == url) {
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+ AM_LOG_RERROR(APLOG_MARK, APLOG_ERR, HTTP_BAD_REQUEST, r,
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+ "URL starts with '///'");
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+ return HTTP_BAD_REQUEST;
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+ }
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+
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return OK;
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}
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--
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2.26.3
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