The ElGamal implementation in Botan through 2.18.1, as used in Thunderbird and other…
Priority LOW 30CWE-327Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-327.
Summary
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.
Why it matters now
EPSS 0.01532 74th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| — | — | all versions | — | No fix listed | CNA |
- — Vendor— Affected all versions Fixed in — No fix listed CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:botan_project:botan:*:*:*:*:*:*:*:* | up to 2.18.1 | Vulnerable | randombit |
| cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* | 34 | Vulnerable | Fedoraproject |
| cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* | 35 | Vulnerable | Fedoraproject |
| cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* | before 91.12.0 | Vulnerable | Mozilla |
- cpe:2.3:a:botan_project:botan:*:*:*:*:*:*:*:* Versions up to 2.18.1 Vulnerable ·randombit
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
- cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* Versions 35 Vulnerable ·Fedoraproject
- cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:* Versions before 91.12.0 Vulnerable ·Mozilla
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Timeline
- 2026-10-02 Threatist record created from CVE-2021-40529
- 2026-10-03 Alias added: GHSA-f9qg-252f-g8cg
References
Sources
- CVE-2021-40529 · CVE Program
- CVE-2021-40529 · NVD
- FIRST EPSS
- GHSA-f9qg-252f-g8cg · GitHub Advisory Database · CC BY 4.0
- CVE-2021-40529 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences