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CVE-2016-7055

Publication date 11 November 2016

Last updated 24 July 2024

Ubuntu priority

Low

Why this priority?

Cvss 3 Severity Score

5.9 · Medium

Score breakdown

There is a carry propagating bug in the Broadwell-specific Montgomery multiplication procedure in OpenSSL 1.0.2 and 1.1.0 before 1.1.0c that handles input lengths divisible by, but longer than 256 bits. Analysis suggests that attacks against RSA, DSA and DH private keys are impossible. This is because the subroutine in question is not used in operations with the private key itself and an input of the attacker's direct choice. Otherwise the bug can manifest itself as transient authentication and key negotiation failures or reproducible erroneous outcome of public-key operations with specially crafted input. Among EC algorithms only Brainpool P-512 curves are affected and one presumably can attack ECDH key negotiation. Impact was not analyzed in detail, because pre-requisites for attack are considered unlikely. Namely multiple clients have to choose the curve in question and the server has to share the private key among them, neither of which is default behaviour. Even then only clients that chose the curve will be affected.

Read the notes from the security team

Status

Package Ubuntu Release Status
openssl 16.10 yakkety
Fixed 1.0.2g-1ubuntu9.1
16.04 LTS xenial
Fixed 1.0.2g-1ubuntu4.6
14.04 LTS trusty
Not affected
12.04 LTS precise
Not affected
openssl098 16.10 yakkety Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
12.04 LTS precise
Not affected

Notes

mdeslaur

only affects 1.0.2 and 1.1.0

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
openssl

Severity score breakdown

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