CVE-2021-40529

MEDIUM
5.9
CVSS Score
Published: September 6, 2021 at 06:45 PM UTC
Updated: June 17, 2026 at 04:07 AM UTC
3 products affected across 3 vendorsFedoraThunderbirdBotan

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Severity
MEDIUM5.9
Exploit prediction
EPSS 2%

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v ≤ 2.18.1
v < 91.12.0
Affected range stops below 91.12.0, so it looks safe — our inference, not a vendor statement

CVSS

Attack Vector
NETWORK
Complexity
HIGH
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-327

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