CVE-2018-10903 PyCA Cryptography vulnerable to GCM tag forgery

What is CVE-2018-10903?

CVE-2018-10903 is a high-severity vulnerability in Canonical Ubuntu Linux, published on 30 Jul 2018. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A flaw was found in python-cryptography versions between >=1.9.0 and <2.3. The finalize_with_tag API did not enforce a minimum tag length. If a user did not validate the input length prior to passing it to finalize_with_tag an attacker could craft an invalid payload with a shortened tag (e.g. 1 byte) such that they would have a 1 in 256 chance of passing the MAC check. GCM tag forgeries can cause key leakage.

Weakness: CWE-20

Which versions are affected by CVE-2018-10903?

3 open source packages ship an affected version, including cryptography. It affects 3 products.

Products include Canonical Ubuntu Linux, Cryptography Python-Cryptography, Redhat Openstack.

How do I fix CVE-2018-10903?

Upgrade cryptography to 2.3 or later.

Is CVE-2018-10903 being exploited?

There is no known exploitation of CVE-2018-10903 in the wild and no public exploit code.

Other vulnerabilities in Canonical Ubuntu Linux

• CVE-2020-11651 SaltStack Salt Authentication Bypass Exploited Critical 9.8
• CVE-2020-7247 OpenSMTPD Remote Code Execution Exploited Critical 9.8
• CVE-2019-16928 Exim Out-of-bounds Write Exploited Critical 9.8
• CVE-2018-6789 Exim Buffer Overflow Exploited Critical 9.8
• CVE-2015-2590 Oracle Java SE and Java SE Embedded Remote Code Execution Exploited Critical 9.8

All Canonical Ubuntu Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as DEBIAN-CVE-2018-10903, GHSA-fcf9-3qw3-gxmj, MGASA-2018-0429, PYSEC-2018-52, RHSA-2018:3600, SUSE-SU-2018:3392-1 and 6 more.