Description
Botan is a C++ cryptography library. Prior to version 3.11.1, the TLS 1.3 implementation allowed ApplicationData records to be processed prior to the Finished message being received. A server which is attempting to enforce client authentication via certificates can by bypassed by a client which entirely omits Certificate, CertificateVerify, and the Finished message and instead sends application data records. This vulnerability is fixed in 3.11.1.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| randombit | botan | < 3.11.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | botan3 | 3.11.0+dfsg-2 | — |
| Debian 13 | botan3 | 3.11.0+dfsg-2 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | botan3 | No fix yet | — |
| Ubuntu 26.04 LTS | botan3 | No fix yet | — |
| Ubuntu 25.10 | botan +1 | No fix yet | — |
| Ubuntu 20.04 LTS | botan | No fix yet | — |
| Ubuntu 18.04 LTS | botan | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 24.04 LTS | botan | No fix yet | — |
| Ubuntu Pro 22.04 LTS | botan | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 16.0 | Botan | 3.7.1-160000.3.1 | openSUSE-SU-2026:20528-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | botan3 | 3.11.1-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | botan2 | No fix yet | — |
Advisories 1
- openSUSE-SU-2026:20528-1 Security update for Botan SUSE / openSUSE Security Updates · Apr 22, 2026