| Name | 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. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| Debian Bugs | 993840 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| botan (PTS) | buster | 2.9.0-2 | vulnerable |
| bullseye | 2.17.3+dfsg-2 | vulnerable | |
| bookworm | 2.19.3+dfsg-1 | fixed | |
| sid, trixie | 2.19.5+dfsg-3 | fixed | |
| botan1.10 (PTS) | jessie, jessie (lts) | 1.10.8-2+deb8u2 | vulnerable |
| stretch (security), stretch (lts), stretch | 1.10.17-1+deb9u1 | vulnerable |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| botan | source | (unstable) | 2.18.1+dfsg-3 | 993840 | ||
| botan1.10 | source | jessie | (unfixed) | end-of-life | ||
| botan1.10 | source | (unstable) | (unfixed) |
[bullseye] - botan <no-dsa> (Minor issue)
[buster] - botan <no-dsa> (Minor issue)
[stretch] - botan1.10 <ignored> (Affected function encrypt(...) has changed drastically. Backport is too instrusive to backport)
https://eprint.iacr.org/2021/923
https://github.com/randombit/botan/pull/2790
Fixed by: https://github.com/randombit/botan/commit/9a23e4e3bc3966340531f2ff608fa9d33b5185a2
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