Bug 1848507 (CVE-2020-13757)

Summary:	CVE-2020-13757 python-rsa: decryption of ciphertext leads to DoS
Product:	[Other] Security Response	Reporter:	Dhananjay Arunesh <darunesh>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED ERRATA	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	apevec, bdettelb, bmontgom, bperkins, dbecker, eparis, hvyas, jburrell, jjoyce, jmontleo, jokerman, jschluet, jschorr, lhh, lpeer, mburns, me, nstielau, rhos-maint, sclewis, slinaber, sponnaga, tomckay, yohangraterol92
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	python-rsa-4.1	Doc Type:	If docs needed, set a value
Doc Text:	A flaw was found in the python-rsa package, where it does not explicitly check the ciphertext length against the key size and ignores the leading 0 bytes during the decryption of the ciphertext. This flaw allows an attacker to perform a ciphertext attack, leading to a denial of service. The highest threat from this vulnerability is to confidentiality.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-08-18 09:15:23 UTC	Type:	---
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:	1851171, 1848508, 1848509, 1850329, 1850330, 1850385, 1850966, 1851172, 1851173, 1851174, 1866148
Bug Blocks:	1848510

Description Dhananjay Arunesh 2020-06-18 13:22:07 UTC

A vulnerability was found in Python-RSA before 4.1 ignores leading '\0' bytes during decryption of ciphertext. This could conceivably have a security-relevant impact, e.g., by helping an attacker to infer that an application uses Python-RSA, or if the length of accepted ciphertext affects application behavior (such as by causing excessive memory allocation).

References:
https://github.com/sybrenstuvel/python-rsa/issues/146
https://github.com/sybrenstuvel/python-rsa/issues/146#issuecomment-641845667

Comment 1 Dhananjay Arunesh 2020-06-18 13:22:57 UTC

Created python-rsa tracking bugs for this issue:

Affects: epel-all [bug 1848509]
Affects: fedora-all [bug 1848508]

Comment 4 Przemyslaw Roguski 2020-06-23 10:14:05 UTC

Upstream patch: https://github.com/sybrenstuvel/python-rsa/commit/93af6f2f89a9bf28361e67716c4240e691520f30

Comment 9 Nick Tait 2020-06-25 17:05:11 UTC

Created python-rsa tracking bugs for this issue:

Affects: openstack-rdo [bug 1851171]

Comment 11 Nick Tait 2020-06-25 17:30:30 UTC

External References:

https://github.com/sybrenstuvel/python-rsa/issues/146

Comment 13 errata-xmlrpc 2020-08-18 05:03:23 UTC

This issue has been addressed in the following products:

  Red Hat OpenShift Container Platform 4.5

Via RHSA-2020:3453 https://access.redhat.com/errata/RHSA-2020:3453

Comment 14 Product Security DevOps Team 2020-08-18 09:15:23 UTC

This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):

https://access.redhat.com/security/cve/cve-2020-13757

Comment 15 errata-xmlrpc 2020-08-26 22:46:55 UTC

This issue has been addressed in the following products:

  Red Hat OpenShift Container Platform 3.11

Via RHSA-2020:3541 https://access.redhat.com/errata/RHSA-2020:3541

Comment 17 Nick Tait 2021-04-03 16:12:37 UTC

Statement:

In Red Hat OpenStack Platform, because the flaw has a lower impact and the fix would require a substantial amount of development, no update will be provided at this time for the RHOSP python-rsa package.