Bug 1794740 (CVE-2020-5390)

Summary:	CVE-2020-5390 python-pysaml2: does not check that the signature in a SAML document is enveloped
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED WONTFIX	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	apevec, apevec, jjoyce, jschluet, lhh, lpeer, mburns, nkinder, sclewis, slinaber
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	python-pysaml2 5.0.0	Doc Type:	If docs needed, set a value
Doc Text:	A verification flaw was found in python-pysaml2, where it did not check that the signature in a SAML document was enveloped, which enabled XML signature wrapping (XSW) attacks. A remote attacker could exploit this flaw to convince SAML processing to verify the signature and accept malicious data. This issue specifically affects the verification of signed SAML assertions.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-10-28 01:55:35 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:	1794741, 1794742, 1795501, 1795502, 1795503
Bug Blocks:	1794743

Description Guilherme de Almeida Suckevicz 2020-01-24 14:06:03 UTC

PySAML2 before 5.0.0 does not check that the signature in a SAML document is enveloped and thus signature wrapping is effective, i.e., it is affected by XML Signature Wrapping (XSW). The signature information and the node/object that is signed can be in different places and thus the signature verification will succeed, but the wrong data will be used. This specifically affects the verification of assertion that have been signed.

References and upstream commits:
https://github.com/IdentityPython/pysaml2/commit/5e9d5acbcd8ae45c4e736ac521fd2df5b1c62e25
https://github.com/IdentityPython/pysaml2/commit/f27c7e7a7010f83380566a219fd6a290a00f2b6e

Comment 1 Guilherme de Almeida Suckevicz 2020-01-24 14:06:23 UTC

Created python-pysaml2 tracking bugs for this issue:

Affects: fedora-all [bug 1794741]
Affects: openstack-rdo [bug 1794742]

Comment 3 Summer Long 2020-01-29 00:30:39 UTC

Statement:

All versions of Red Hat OpenStack Platform ship but do not use the flawed check-signature functionality of python-pysaml2. The impact for these products is therefore rated as having a security impact of Low.

Comment 5 Summer Long 2020-01-29 00:55:08 UTC

Mitigation:

There is no known mitigation for this issue, the flaw can only be resolved by applying updates.