diff -Nru strongswan-5.5.1/debian/changelog strongswan-5.5.1/debian/changelog
--- strongswan-5.5.1/debian/changelog	2017-05-24 18:53:29.000000000 +0000
+++ strongswan-5.5.1/debian/changelog	2017-08-15 18:00:33.000000000 +0000
@@ -1,3 +1,13 @@
+strongswan (5.5.1-1ubuntu3.2) zesty-security; urgency=medium
+
+  * SECURITY UPDATE: Fix RSA signature verification
+    - debian/patches/CVE-2017-11185.patch: does some
+      verifications in order to avoid null-point dereference
+      in src/libstrongswan/gmp/gmp_rsa_public_key.c
+    - CVE-2017-11185
+
+ -- Leonidas S. Barbosa <leo.barbosa@canonical.com>  Tue, 15 Aug 2017 15:00:33 -0300
+
 strongswan (5.5.1-1ubuntu3.1) zesty-security; urgency=medium
 
   * SECURITY UPDATE: Insufficient Input Validation in gmp Plugin
diff -Nru strongswan-5.5.1/debian/patches/CVE-2017-11185.patch strongswan-5.5.1/debian/patches/CVE-2017-11185.patch
--- strongswan-5.5.1/debian/patches/CVE-2017-11185.patch	1970-01-01 00:00:00.000000000 +0000
+++ strongswan-5.5.1/debian/patches/CVE-2017-11185.patch	2017-08-15 17:46:48.000000000 +0000
@@ -0,0 +1,50 @@
+From ed282e9a463c068146c945984fdea7828e663861 Mon Sep 17 00:00:00 2001
+From: Tobias Brunner <tobias@strongswan.org>
+Date: Mon, 29 May 2017 11:59:34 +0200
+Subject: [PATCH] gmp: Fix RSA signature verification for m >= n
+
+By definition, m must be <= n-1, we didn't enforce that and because
+mpz_export() returns NULL if the passed value is zero a crash could have
+been triggered with m == n.
+
+Fixes CVE-2017-11185.
+---
+ src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c | 12 +++++++++---
+ 1 file changed, 9 insertions(+), 3 deletions(-)
+
+diff --git a/src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c b/src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c
+index 32a72ac9600b..a741f85d4f62 100644
+--- a/src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c
++++ b/src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c
+@@ -78,11 +78,17 @@ static chunk_t rsaep(private_gmp_rsa_public_key_t *this, chunk_t data)
+ 	mpz_t m, c;
+ 	chunk_t encrypted;
+ 
+-	mpz_init(c);
+ 	mpz_init(m);
+-
+ 	mpz_import(m, data.len, 1, 1, 1, 0, data.ptr);
+ 
++	if (mpz_cmp_ui(m, 0) <= 0 || mpz_cmp(m, this->n) >= 0)
++	{	/* m must be <= n-1, but 0 is a valid value, doesn't really make sense
++		 * here, though */
++		mpz_clear(m);
++		return chunk_empty;
++	}
++
++	mpz_init(c);
+ 	mpz_powm(c, m, this->e, this->n);
+ 
+ 	encrypted.len = this->k;
+@@ -150,7 +156,7 @@ static bool verify_emsa_pkcs1_signature(private_gmp_rsa_public_key_t *this,
+ 	 */
+ 
+ 	/* check magic bytes */
+-	if (*(em.ptr) != 0x00 || *(em.ptr+1) != 0x01)
++	if (em.len < 2 || *(em.ptr) != 0x00 || *(em.ptr+1) != 0x01)
+ 	{
+ 		goto end;
+ 	}
+-- 
+2.7.4
+
diff -Nru strongswan-5.5.1/debian/patches/series strongswan-5.5.1/debian/patches/series
--- strongswan-5.5.1/debian/patches/series	2017-05-24 18:53:23.000000000 +0000
+++ strongswan-5.5.1/debian/patches/series	2017-08-15 17:47:03.000000000 +0000
@@ -5,3 +5,4 @@
 increase-bliss-test-timeout.patch
 CVE-2017-9022.patch
 CVE-2017-9023.patch
+CVE-2017-11185.patch