Bug 1602752

Summary:	Possible tag truncation security bug in AEAD API
Product:	[Fedora] Fedora	Reporter:	Christian Heimes <cheimes>
Component:	python-cryptography	Assignee:	Jeremy Cline <jeremy>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	urgent	Docs Contact:
Priority:	unspecified
Version:	28	CC:	cheimes, itamar, jeremy, nick, npmccallum, rbarlow, terrycwk1994
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	All
Whiteboard:
Fixed In Version:	python-cryptography-2.3-1.fc28 python-cryptography-2.3-1.fc27	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:
Clones:	1602755 (view as bug list)		Environment:
Last Closed:	2018-07-22 03:03:54 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1602755

Description Christian Heimes 2018-07-18 12:24:57 UTC

Description of problem:
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.

Version-Release number of selected component (if applicable):
All versions between >=1.9.0 and <2.3
* python-cryptography-2.0.2-4.fc27
* python-cryptography-2.2.1-1.fc28
* python-cryptography-2.2.1-3.fc29

EL7 only contains python-cryptography-1.7.2-1.el7_4.1, so it's not affected.

How reproducible:
always

Additional info:
The issue was fixed by PR https://github.com/pyca/cryptography/pull/4342 and in upstream release 2.3 (released today). The security issue is already public knowledge.

Comment 1 Fedora Update System 2018-07-18 14:15:58 UTC

python-cryptography-2.3-1.fc28 python-cryptography-vectors-2.3-1.fc28 has been submitted as an update to Fedora 28. https://bodhi.fedoraproject.org/updates/FEDORA-2018-a9fe5e183e

Comment 2 Fedora Update System 2018-07-18 14:16:07 UTC

python-cryptography-2.3-1.fc27 python-cryptography-vectors-2.3-1.fc27 has been submitted as an update to Fedora 27. https://bodhi.fedoraproject.org/updates/FEDORA-2018-06c24068c6

Comment 3 Fedora Update System 2018-07-19 17:29:25 UTC

python-cryptography-2.3-1.fc27, python-cryptography-vectors-2.3-1.fc27 has been pushed to the Fedora 27 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-06c24068c6

Comment 4 Fedora Update System 2018-07-19 20:20:40 UTC

python-cryptography-2.3-1.fc28, python-cryptography-vectors-2.3-1.fc28 has been pushed to the Fedora 28 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2018-a9fe5e183e

Comment 5 Fedora Update System 2018-07-22 03:03:54 UTC

python-cryptography-2.3-1.fc28, python-cryptography-vectors-2.3-1.fc28 has been pushed to the Fedora 28 stable repository. If problems still persist, please make note of it in this bug report.

Comment 6 Fedora Update System 2018-07-31 17:10:38 UTC

python-cryptography-2.3-1.fc27, python-cryptography-vectors-2.3-1.fc27 has been pushed to the Fedora 27 stable repository. If problems still persist, please make note of it in this bug report.