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AUSCERT External Security Bulletin Redistribution
USN-4378-1: Flask vulnerability
2 June 2020
AusCERT Security Bulletin Summary
Operating System: Ubuntu
Impact/Access: Denial of Service -- Remote/Unauthenticated
CVE Names: CVE-2018-1000656
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USN-4378-1: Flask vulnerability
1 June 2020
A security issue affects these releases of Ubuntu and its derivatives:
o Ubuntu 18.04 LTS
o Ubuntu 16.04 LTS
o Ubuntu 14.04 ESM
Flask could be made to consume a large amount of memory if it received a
specially crafted input.
o flask - Micro web framework based on Werkzeug and Jinja2
It was discovered that Flask incorrectly handled certain inputs. An attacker
could possibly use this issue to cause a denial of service.
The problem can be corrected by updating your system to the following package
Ubuntu 18.04 LTS
python-flask - 0.12.2-3ubuntu0.1
python3-flask - 0.12.2-3ubuntu0.1
Ubuntu 16.04 LTS
python-flask - 0.10.1-2ubuntu0.1
python3-flask - 0.10.1-2ubuntu0.1
Ubuntu 14.04 ESM
python-flask - 0.10.1-2ubuntu0.1~esm1
python3-flask - 0.10.1-2ubuntu0.1~esm1
To update your system, please follow these instructions: https://
In general, a standard system update will make all the necessary changes.
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