# CVE-2018-10903: python3-cryptography: A flaw was found in python-cryptography versions between >=1.9.0 and <2.3

CVE-2018-10903 is fixed in 2 products on 1 platform, first by python-cryptography 2.1.4-1ubuntu1.2, released July 19, 2018. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2018-10903
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.0320
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 19, 2018

## 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | python-cryptography Ubuntu 18.04.6 LTS (bionic) | 2.1.4-1ubuntu1.2 | [python-cryptography 2.1.4-1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python-cryptography-2.1.4-1ubuntu1.2.md) | Jul 19, 2018 |
| Linux | python3-cryptography Ubuntu 18.04.6 LTS (bionic) | 2.1.4-1ubuntu1.2 | [python3-cryptography 2.1.4-1ubuntu1.2](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-python3-cryptography-2.1.4-1ubuntu1.2.md) | Jul 19, 2018 |

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