Bug 2002825 (CVE-2021-40529) - CVE-2021-40529 botan: ElGamal implementation allows plaintext recovery
Summary: CVE-2021-40529 botan: ElGamal implementation allows plaintext recovery
Keywords:
Status: CLOSED UPSTREAM
Alias: CVE-2021-40529
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
URL:
Whiteboard:
Depends On: 2002826 2002827 2002828 2002829
Blocks:
TreeView+ depends on / blocked
 
Reported: 2021-09-09 19:25 UTC by Guilherme de Almeida Suckevicz
Modified: 2021-09-10 00:21 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed: 2021-09-10 00:21:14 UTC
Embargoed:

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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.
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