Bug 2002825 (CVE-2021-40529)

Summary:	CVE-2021-40529 botan: ElGamal implementation allows plaintext recovery
Product:	[Other] Security Response	Reporter:	Guilherme de Almeida Suckevicz <gsuckevi>
Component:	vulnerability	Assignee:	Red Hat Product Security <security-response-team>
Status:	CLOSED UPSTREAM	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	bkircher, thomas.moschny
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2021-09-10 00:21:14 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:	2002828, 2002826, 2002827, 2002829
Bug Blocks:

Description Guilherme de Almeida Suckevicz 2021-09-09 19:25:52 UTC

The ElGamal implementation in Botan through 2.18.1, as used in Thunderbird and other products, allows plaintext recovery because, during interaction between two cryptographic libraries, a certain dangerous combination of the prime defined by the receiver's public key, the generator defined by the receiver's public key, and the sender's ephemeral exponents can lead to a cross-configuration attack against OpenPGP.

References:
https://ibm.github.io/system-security-research-updates/2021/07/20/insecurity-elgamal-pt1
https://ibm.github.io/system-security-research-updates/2021/09/06/insecurity-elgamal-pt2
https://eprint.iacr.org/2021/923

Upstream patch:
https://github.com/randombit/botan/pull/2790

Comment 1 Guilherme de Almeida Suckevicz 2021-09-09 19:26:16 UTC

Created botan tracking bugs for this issue:

Affects: epel-7 [bug 2002828]
Affects: fedora-all [bug 2002826]


Created botan2 tracking bugs for this issue:

Affects: epel-8 [bug 2002829]
Affects: fedora-all [bug 2002827]

Comment 2 Product Security DevOps Team 2021-09-10 00:21:14 UTC

This CVE Bugzilla entry is for community support informational purposes only as it does not affect a package in a commercially supported Red Hat product. Refer to the dependent bugs for status of those individual community products.