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Published: 7 February 2023

A timing based side channel exists in the OpenSSL RSA Decryption implementation which could be sufficient to recover a plaintext across a network in a Bleichenbacher style attack. To achieve a successful decryption an attacker would have to be able to send a very large number of trial messages for decryption. The vulnerability affects all RSA padding modes: PKCS#1 v1.5, RSA-OEAP and RSASVE. For example, in a TLS connection, RSA is commonly used by a client to send an encrypted pre-master secret to the server. An attacker that had observed a genuine connection between a client and a server could use this flaw to send trial messages to the server and record the time taken to process them. After a sufficiently large number of messages the attacker could recover the pre-master secret used for the original connection and thus be able to decrypt the application data sent over that connection.


Due to the substantial code changes required to fix this side
channel issue and others like it in the 1.0.2 and earlier
codebases, we will not be fixing this issue in bionic and
earlier to not introduce possible regressions.

The commit was later reverted, and a more simplified fix was
used, see:;a=commit;h=0372649a943fb23f7f08c7acdbc01464b9df03f0;a=commit;h=3f499b24f3bcd66db022074f7e8b4f6ee266a3ae



Cvss 3 Severity Score


Score breakdown


Package Release Status
Launchpad, Ubuntu, Debian
bionic Needs triage

focal Needs triage

jammy Needs triage

kinetic Ignored
(end of life, was needs-triage)
lunar Ignored
(end of life, was needs-triage)
mantic Not vulnerable
noble Not vulnerable
trusty Ignored
(end of standard support)
upstream Needs triage

xenial Needs triage

Launchpad, Ubuntu, Debian
bionic Not vulnerable
(uses system openssl1.0)
focal Not vulnerable
(uses system openssl)
Released (12.22.9~dfsg-1ubuntu3.3)
kinetic Not vulnerable
(uses system openssl)
lunar Not vulnerable
(uses system openssl)
mantic Not vulnerable
(uses system openssl)
noble Not vulnerable
(uses system openssl)
trusty Not vulnerable
(uses system openssl)
upstream Needs triage

xenial Not vulnerable
(code not present)
Launchpad, Ubuntu, Debian
Released (1.1.1-1ubuntu2.1~18.04.21)
Released (1.1.1f-1ubuntu2.17)
Released (3.0.2-0ubuntu1.8)
Released (3.0.5-2ubuntu2.1)
Released (3.0.8-1ubuntu1)
Released (3.0.8-1ubuntu1)
Released (3.0.8-1ubuntu1)
trusty Ignored

Released (3.0.8,1.1.1t)
xenial Ignored

Launchpad, Ubuntu, Debian
bionic Ignored

focal Does not exist

jammy Does not exist

kinetic Does not exist

trusty Does not exist

upstream Needs triage

xenial Does not exist

Severity score breakdown

Parameter Value
Base score 5.9
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact None
Availability impact None
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N