CVE-2019-14857 (Other, published 2019-11-26T12:15Z)
Description: value: A flaw was found in mod_auth_openidc before version 2.4.0.1. An open redirect issue exists in URLs with trailing slashes similar to CVE-2019-3877 in mod_auth_mellon.
Severity: MEDIUM (CVSS v3 base score: 6.1)
Weakness: CWE-601 \u2014 URL Redirection to Untrusted Site ('Open Redirect')
A web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a Redirect. This simplifies phishing attacks.
Repository: https://github.com/zmartzone/mod_auth_openidc
Files changed:
AUTHORS
ChangeLog
configure.ac
src/mod_auth_openidc.c
Commit message: improve validation of the post-logout URL; closes #449

- to avoid an open redirect; thanks AIMOTO Norihito
- release 2.4.0.1

Signed-off-by: Hans Zandbelt <hans.zandbelt@zmartzone.eu>

Vulnerable code:
        Janusz Ulanowski <https://github.com/janul>
AC_INIT([mod_auth_openidc],[2.4.0],[hans.zandbelt@zmartzone.eu])

		const char *error_description = NULL;
		apr_uri_t uri;

		if (apr_uri_parse(r->pool, url, &uri) != APR_SUCCESS) {
			const char *error_description = apr_psprintf(r->pool,
					"Logout URL malformed: %s", url);
			oidc_error(r, "%s", error_description);
			return oidc_util_html_send_error(r, c->error_template,
					"Malformed URL", error_description,
					HTTP_INTERNAL_SERVER_ERROR);

		}

		const char *c_host = oidc_get_current_url_host(r);
		if ((uri.hostname != NULL)
				&& ((strstr(c_host, uri.hostname) == NULL)
						|| (strstr(uri.hostname, c_host) == NULL))) {
			error_description =
					apr_psprintf(r->pool,
							"logout value \"%s\" does not match the hostname of the current request \"%s\"",
							apr_uri_unparse(r->pool, &uri, 0), c_host);
			oidc_error(r, "%s", error_description);
			return oidc_util_html_send_error(r, c->error_template,
					"Invalid Request", error_description,
					HTTP_INTERNAL_SERVER_ERROR);
		}

		/* validate the URL to prevent HTTP header splitting */
		if (((strstr(url, "\n") != NULL) || strstr(url, "\r") != NULL)) {
			error_description =
					apr_psprintf(r->pool,
							"logout value \"%s\" contains illegal \"\n\" or \"\r\" character(s)",
							url);
			oidc_error(r, "%s", error_description);
			return oidc_util_html_send_error(r, c->error_template,
					"Invalid Request", error_description,
					HTTP_INTERNAL_SERVER_ERROR);

Fixed code:
	Janusz Ulanowski <https://github.com/janul>
	AIMOTO Norihito

10/02/2019
- improve validation of the post-logout URL parameter on logout; thanks AIMOTO Norihito; closes #449
- release 2.4.0.1

AC_INIT([mod_auth_openidc],[2.4.0.1],[hans.zandbelt@zmartzone.eu])
static apr_byte_t oidc_validate_post_logout_url(request_rec *r, const char *url,
		char **err_str, char **err_desc) {
	apr_uri_t uri;
	const char *c_host = NULL;

	if (apr_uri_parse(r->pool, url, &uri) != APR_SUCCESS) {
		*err_str = apr_pstrdup(r->pool, "Malformed URL");
		*err_desc = apr_psprintf(r->pool, "Logout URL malformed: %s", url);
		oidc_error(r, "%s: %s", *err_str, *err_desc);
		return FALSE;
	}

	c_host = oidc_get_current_url_host(r);
	if ((uri.hostname != NULL)
			&& ((strstr(c_host, uri.hostname) == NULL)
					|| (strstr(uri.hostname, c_host) == NULL))) {
		*err_str = apr_pstrdup(r->pool, "Invalid Request");
		*err_desc =
				apr_psprintf(r->pool,
						"logout value \"%s\" does not match the hostname of the current request \"%s\"",
						apr_uri_unparse(r->pool, &uri, 0), c_host);
		oidc_error(r, "%s: %s", *err_str, *err_desc);
		return FALSE;
	} else if (strstr(url, "/") != url) {
		*err_str = apr_pstrdup(r->pool, "Malformed URL");
		*err_desc =
				apr_psprintf(r->pool,
						"No hostname was parsed and it does not seem to be relative, i.e starting with '/': %s",
						url);
		oidc_error(r, "%s: %s", *err_str, *err_desc);
		return FALSE;
	}

	/* validate the URL to prevent HTTP header splitting */
	if (((strstr(url, "\n") != NULL) || strstr(url, "\r") != NULL)) {
		*err_str = apr_pstrdup(r->pool, "Invalid Request");
		*err_desc =
				apr_psprintf(r->pool,
						"logout value \"%s\" contains illegal \"\n\" or \"\r\" character(s)",
						url);
		oidc_error(r, "%s: %s", *err_str, *err_desc);
		return FALSE;
	}

	return TRUE;
}

	char *error_str = NULL;
	char *error_description = NULL;

		if (oidc_validate_post_logout_url(r, url, &error_str,
				&error_description) == FALSE) {
			return oidc_util_html_send_error(r, c->error_template, error_str,
					error_description,
					HTTP_BAD_REQUEST);