diff -Nru python-cryptography-1.2.3/debian/changelog python-cryptography-1.2.3/debian/changelog
--- python-cryptography-1.2.3/debian/changelog	2018-10-18 11:19:53.000000000 +0000
+++ python-cryptography-1.2.3/debian/changelog	2020-10-28 15:54:43.000000000 +0000
@@ -1,3 +1,13 @@
+python-cryptography (1.2.3-1ubuntu0.3) xenial-security; urgency=medium
+
+  * SECURITY UPDATE: Bleichenbacher timing oracle attack
+    - debian/patches/CVE-2020-25659.patch: Attempt to mitigate
+      Bleichenbacher attacks on RSA decryption docs/spelling_wordlist.txt,
+      src/cryptography/hazmat/backends/openssl/rsa.py.
+    - CVE-2020-25659
+
+ -- Leonidas S. Barbosa <leo.barbosa@canonical.com>  Wed, 28 Oct 2020 11:55:13 -0300
+
 python-cryptography (1.2.3-1ubuntu0.2) xenial-security; urgency=medium
 
   * debian/patches/add_x509_up_ref.patch: add X509_up_ref function for
diff -Nru python-cryptography-1.2.3/debian/patches/CVE-2020-25659.patch python-cryptography-1.2.3/debian/patches/CVE-2020-25659.patch
--- python-cryptography-1.2.3/debian/patches/CVE-2020-25659.patch	1970-01-01 00:00:00.000000000 +0000
+++ python-cryptography-1.2.3/debian/patches/CVE-2020-25659.patch	2020-10-28 14:55:06.000000000 +0000
@@ -0,0 +1,55 @@
+Backported of:
+
+From 58494b41d6ecb0f56b7c5f05d5f5e3ca0320d494 Mon Sep 17 00:00:00 2001
+From: Alex Gaynor <alex.gaynor@gmail.com>
+Date: Sun, 25 Oct 2020 21:16:42 -0400
+Subject: [PATCH] Attempt to mitigate Bleichenbacher attacks on RSA decryption
+ (#5507)
+
+---
+ docs/spelling_wordlist.txt                      |  1 +
+ src/cryptography/hazmat/backends/openssl/rsa.py | 14 +++++++++++---
+ 2 files changed, 12 insertions(+), 3 deletions(-)
+
+diff --git a/docs/spelling_wordlist.txt b/docs/spelling_wordlist.txt
+index 6def795..5afb6c6 100644
+--- a/docs/spelling_wordlist.txt
++++ b/docs/spelling_wordlist.txt
+@@ -2,6 +2,7 @@ affine
+ backend
+ backends
+ bcrypt
++Bleichenbacher
+ Backends
+ Blowfish
+ boolean
+diff --git a/src/cryptography/hazmat/backends/openssl/rsa.py b/src/cryptography/hazmat/backends/openssl/rsa.py
+index 033cd3b..218a1c8 100644
+--- a/src/cryptography/hazmat/backends/openssl/rsa.py
++++ b/src/cryptography/hazmat/backends/openssl/rsa.py
+@@ -100,11 +100,19 @@ def _enc_dec_rsa_pkey_ctx(backend, key, data, padding_enum):
+     backend.openssl_assert(buf_size > 0)
+     outlen = backend._ffi.new("size_t *", buf_size)
+     buf = backend._ffi.new("char[]", buf_size)
++    # Everything from this line onwards is written with the goal of being as
++    # constant-time as is practical given the constraints of Python and our
++    # API. See Bleichenbacher's '98 attack on RSA, and its many many variants.
++    # As such, you should not attempt to change this (particularly to "clean it
++    # up") without understanding why it was written this way (see
++    # Chesterton's Fence), and without measuring to verify you have not
++    # introduced observable time differences.
+     res = crypt(pkey_ctx, buf, outlen, data, len(data))
++    resbuf = backend._ffi.buffer(buf)[: outlen[0]]
++    backend._lib.ERR_clear_error()
+     if res <= 0:
+-        _handle_rsa_enc_dec_error(backend, key)
+-
+-    return backend._ffi.buffer(buf)[:outlen[0]]
++        raise ValueError("Encryption/decryption failed.")
++    return resbuf
+ 
+ 
+ def _enc_dec_rsa_098(backend, key, data, padding_enum):
+-- 
+2.25.1
+
diff -Nru python-cryptography-1.2.3/debian/patches/series python-cryptography-1.2.3/debian/patches/series
--- python-cryptography-1.2.3/debian/patches/series	2018-10-18 11:17:38.000000000 +0000
+++ python-cryptography-1.2.3/debian/patches/series	2020-10-28 14:55:06.000000000 +0000
@@ -1,3 +1,4 @@
 0001-Actually-allocate-a-buffer-that-is-the-correct-size.patch
 CVE-2016-9243.patch
 add_x509_up_ref.patch
+CVE-2020-25659.patch