mod_auth_mellon/0001-Prevent-redirect-to-URLs-that-begin-with.patch

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