# CVE-2021-40529: Mozilla Thunderbird and 1 other: The ElGamal implementation in Botan through 2.18.1, as used in Thunderbird and other products, allows…

CVE-2021-40529 is fixed in Mozilla Thunderbird (en-US) on 1 platform by Mozilla Thunderbird (en-US) 102.0 (version 102.0), released June 29, 2022. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-40529
- Priority: Routine
- CVSS: 5.9
- EPSS: 0.0153
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 6, 2021
- Vendor advisory: https://nvd.nist.gov/vuln/detail/CVE-2021-40529

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Windows apps | Mozilla Thunderbird (en-US) | 102.0 | [Mozilla Thunderbird (en-US) 102.0](https://patchblox.com/security/data/fix/windows-app/mozilla.thunderbird-102.0.md) | Jun 29, 2022 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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