Description
ALPACA is an application layer protocol content confusion attack, exploiting TLS servers implementing different protocols but using compatible certificates, such as multi-domain or wildcard certificates. A MiTM attacker having access to victim's traffic at the TCP/IP layer can redirect traffic from one subdomain to another, resulting in a valid TLS session. This breaks the authentication of TLS and cross-protocol attacks may be possible where the behavior of one protocol service may compromise the other at the application layer.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | ALPACA | vsftpd 3.0.4, nginx 1.21.0, sendmail 8.17 | — |
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 | nginx | 1.20.2-2 | — |
| Debian 14 | sendmail | 8.16.1-2 | — |
| Debian 14 | vsftpd | 3.0.5-0.1 | — |
| Debian 13 | nginx | 1.20.2-2 | — |
| Debian 13 | sendmail | 8.16.1-2 | — |
| Debian 13 | vsftpd | 3.0.5-0.1 | — |
| Debian 12 | nginx | 1.20.2-2 | — |
| Debian 12 | sendmail | 8.16.1-2 | — |
| Debian 12 | vsftpd | No fix yet | — |
| Debian 10 | nginx | 1.14.2-2+deb10u5 | DLA-3203-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | nginx | 1.18.0-6ubuntu14.1 | USN-5371-2 |
| Ubuntu 22.04 LTS | sendmail | No fix yet | — |
| Ubuntu 20.04 LTS | nginx | 1.18.0-0ubuntu1.3 | USN-5371-1 |
| Ubuntu 20.04 LTS | sendmail | No fix yet | — |
| Ubuntu 20.04 LTS | vsftpd | 3.0.5-0ubuntu0.20.04.1 | USN-6379-1 |
| Ubuntu 18.04 LTS | nginx | 1.14.0-0ubuntu1.10 | USN-5371-1 |
| Ubuntu 18.04 LTS | vsftpd +1 | No fix yet | — |
| Ubuntu 16.04 LTS | vsftpd +1 | No fix yet | — |
| Ubuntu 14.04 LTS | vsftpd +1 | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 16.04 LTS | nginx | 1.10.3-0ubuntu0.16.04.5+esm3 | USN-5371-1 |
| Ubuntu Pro 14.04 LTS | nginx | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP4 | vsftpd | 3.0.5-150400.3.3.1 | SUSE-SU-2022:3320-1 |
| SLES 15 SP3 | nginx | 1.19.8-150300.3.9.1 | SUSE-SU-2022:4201-1 |
| SLES 15 SP3 | vsftpd | 3.0.5-150200.12.9.1 | SUSE-SU-2022:3457-1 |
| SLES 15 SP2 | nginx | 1.16.1-150200.3.9.1 | SUSE-SU-2022:4265-1 |
| SLES 15 SP2 | vsftpd | 3.0.5-150200.12.9.1 | SUSE-SU-2022:3457-1 |
| SLES 15 SP1 | nginx | 1.16.1-150100.6.16.1 | SUSE-SU-2022:4266-1 |
| SLES 15 SP1 | vsftpd | 3.0.5-150000.7.19.1 | SUSE-SU-2022:3458-1 |
| SLES 15 | nginx | 1.16.1-150000.3.18.1 | SUSE-SU-2022:4192-1 |
| SLES 15 | vsftpd | 3.0.5-150000.7.19.1 | SUSE-SU-2022:3458-1 |
Show 13 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP5 | vsftpd | 3.0.5-47.7.1 | SUSE-SU-2022:3888-1, SUSE-SU-2022:3383-1, SUSE-RU-2022:0655-1 |
| SLES for SAP 15 SP2 | nginx | 1.16.1-150200.3.9.1 | SUSE-SU-2022:4265-1 |
| SLES for SAP 15 SP2 | vsftpd | 3.0.5-150200.12.9.1 | SUSE-SU-2022:3457-1 |
| SLES for SAP 15 SP1 | nginx | 1.16.1-150100.6.16.1 | SUSE-SU-2022:4266-1 |
| SLES for SAP 15 SP1 | vsftpd | 3.0.5-150000.7.19.1 | SUSE-SU-2022:3458-1 |
| SLES for SAP 15 | nginx | 1.16.1-150000.3.18.1 | SUSE-SU-2022:4192-1 |
| SLES for SAP 15 | vsftpd | 3.0.5-150000.7.19.1 | SUSE-SU-2022:3458-1 |
| SLES for SAP 12 SP5 | vsftpd | 3.0.5-47.7.1 | SUSE-SU-2022:3888-1, SUSE-SU-2022:3383-1, SUSE-RU-2022:0655-1 |
| SLE HPC 15 SP2 | nginx | 1.16.1-150200.3.9.1 | SUSE-SU-2022:4265-1 |
| SLE HPC 15 SP2 | vsftpd | 3.0.5-150200.12.9.1 | SUSE-SU-2022:3457-1 |
| SLE HPC 15 SP1 | nginx | 1.16.1-150100.6.16.1 | SUSE-SU-2022:4266-1 |
| SLE HPC 15 SP1 | vsftpd | 3.0.5-150000.7.19.1 | SUSE-SU-2022:3458-1 |
| SLE HPC 15 | nginx | 1.16.1-150000.3.18.1 | SUSE-SU-2022:4192-1 |
| SLE HPC 15 | vsftpd | 3.0.5-150000.7.19.1 | SUSE-SU-2022:3458-1 |
| SUSE Manager Server 4.1 | nginx | 1.16.1-150200.3.9.1 | SUSE-SU-2022:4265-1 |
| SUSE Manager Server 4.1 | vsftpd | 3.0.5-150200.12.9.1 | SUSE-SU-2022:3457-1 |
| SUSE Manager Retail Branch Server 4.1 | nginx | 1.16.1-150200.3.9.1 | SUSE-SU-2022:4265-1 |
| SUSE Manager Retail Branch Server 4.1 | vsftpd | 3.0.5-150200.12.9.1 | SUSE-SU-2022:3457-1 |
| SUSE Manager Proxy 4.1 | nginx | 1.16.1-150200.3.9.1 | SUSE-SU-2022:4265-1 |
| SUSE Manager Proxy 4.1 | vsftpd | 3.0.5-150200.12.9.1 | SUSE-SU-2022:3457-1 |
| SUSE Enterprise Storage 7 | nginx | 1.16.1-150200.3.9.1 | SUSE-SU-2022:4265-1 |
| SUSE Enterprise Storage 7 | vsftpd | 3.0.5-150200.12.9.1 | SUSE-SU-2022:3457-1 |
| SUSE Enterprise Storage 6 | nginx | 1.16.1-150100.6.16.1 | SUSE-SU-2022:4266-1 |
| SUSE Enterprise Storage 6 | vsftpd | 3.0.5-150000.7.19.1 | SUSE-SU-2022:3458-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.4 | nginx | 1.19.8-150300.3.9.1 | SUSE-SU-2022:4201-1 |
| openSUSE Leap 15.4 | vsftpd | 3.0.5-150400.3.3.1 | SUSE-SU-2022:3320-1 |
| openSUSE Leap 15.3 | nginx | 1.19.8-150300.3.9.1 | SUSE-SU-2022:4201-1 |
| openSUSE Leap 15.3 | vsftpd | 3.0.5-150200.12.9.1 | SUSE-SU-2022:3457-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | nginx | 1.20.1-r1 | — |
| Alpine v3.23 | nginx | 1.20.1-r1 | — |
| Alpine v3.22 | nginx | 1.20.1-r1 | — |
| Alpine v3.21 | nginx | 1.20.1-r1 | — |
| Alpine v3.20 | nginx | 1.20.1-r1 | — |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | nginx | 1.20.1-r1 | — |
| Alpine v3.18 | nginx | 1.20.1-r1 | — |
| Alpine v3.17 | nginx | 1.20.1-r1 | — |
| Alpine v3.16 | nginx | 1.20.1-r1 | — |
| Alpine v3.15 | nginx | 1.20.1-r1 | — |
| Alpine v3.14 | nginx | 1.20.1-r1 | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | nginx +9 | 1:1.22.1-1.amzn2023.0.2 | ALAS2023-2023-099 |
| Amazon Linux 2023 | sendmail +4 | 8.17.1-5.amzn2023.0.4 | ALAS2023-2023-018 |
| Amazon Linux 2023 | vsftpd | 3.0.5-1.amzn2023.0.2 | ALAS2023-2023-019 |
| Amazon Linux 2 | vsftpd +1 | 3.0.2-25.amzn2.0.1 | ALAS2-2024-2431 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | nginx | 1.20.2-2 | — |
| Azure Linux 2 (CBL-Mariner) | sendmail | No fix yet | — |
| Azure Linux 2 (CBL-Mariner) | vsftpd | 3.0.5-1 | — |
Advisories 22
- WID-SEC-2023-2031 Xerox FreeFlow Print Server: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 11, 2026
- USN-5371-1 nginx vulnerabilities Ubuntu Security Notices (USN) · Jun 25, 2026
- USN-5371-2 nginx vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- USN-6379-1 vsftpd vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- DLA-3203-1 nginx - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2022:3320-1 Security update for vsftpd SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:3457-1 Security update for vsftpd SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:3888-1 Security update for vsftpd SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:3383-1 Security update for vsftpd SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:3458-1 Security update for vsftpd SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:4201-1 Security update for nginx SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:4265-1 Security update for nginx SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-RU-2022:0655-1 Recommended update for vsftpd SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:4192-1 Security update for nginx SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:4266-1 Security update for nginx SUSE / openSUSE Security Updates · Feb 4, 2026
- SCA-2025-0011 Vulnerabilities affecting Endress+Hauser SSG-E210GC SICK PSIRT · Oct 2, 2025
- SCA-2025-0009 Vulnerabilities affecting SICK TDC-E210GC SICK PSIRT · Aug 1, 2025
- WID-SEC-2022-1482 TLS Implementierungen: Schwachstelle ermöglicht Umgehen von Sicherheitsvorkehrungen BSI CERT-Bund (WID) · Nov 3, 2024
- ALAS2023-2023-099 Moderate: nginx security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Feb 15, 2024
- ALAS2-2024-2431 Moderate: vsftpd security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Jan 22, 2024
- ALAS2023-2023-019 Moderate: vsftpd security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Feb 22, 2023
- ALAS2023-2023-018 Moderate: sendmail security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Feb 22, 2023