Description
A flaw was found in libssh versions built with OpenSSL versions older than 3.0, specifically in the ssh_kdf() function responsible for key derivation. Due to inconsistent interpretation of return values where OpenSSL uses 0 to indicate failure and libssh uses 0 for success—the function may mistakenly return a success status even when key derivation fails. This results in uninitialized cryptographic key buffers being used in subsequent communication, potentially compromising SSH sessions' confidentiality, integrity, and availability.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| libssh | libssh | < 0.11.2 | 0.11.2 |
| Red Hat | Red Hat Enterprise Linux 8 | — | — |
| Red Hat | Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On | — | — |
| Red Hat | Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support | — | — |
| Red Hat | Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On | — | — |
| Red Hat | Red Hat Enterprise Linux 8.8 Telecommunications Update Service | — | — |
| Red Hat | Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions | — | — |
| Red Hat | Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions | — | — |
| Red Hat | Red Hat Enterprise Linux 10 | — | — |
| Red Hat | Red Hat Enterprise Linux 6 | — | — |
| Red Hat | Red Hat Enterprise Linux 7 | — | — |
| Red Hat | Red Hat Enterprise Linux 9 | — | — |
| Red Hat | Red Hat OpenShift Container Platform 4 | — | — |
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 | libssh | 0.11.2-1 | — |
| Debian 13 | libssh | 0.11.2-1 | — |
| Debian 12 | libssh | 0.10.6-0+deb12u2 | — |
| Debian 11 | libssh | 0.9.8-0+deb11u2 | DLA-4385-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | libssh | 0.10.6-2ubuntu0.1 | USN-7619-1 |
| Ubuntu 22.04 LTS | libssh | 0.9.6-2ubuntu0.22.04.4 | USN-7619-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | libssh | No fix yet | — |
| Ubuntu Pro 18.04 LTS | libssh | No fix yet | — |
| Ubuntu Pro 16.04 LTS | libssh | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 8 | libssh +2 | 0.9.6-16.el8_10 | RHSA-2025:21977 |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 9.0 E4S | libssh +2 | 0.9.6-3.el9_0.2 | RHSA-2025:23024 |
| RHEL 8.8 TUS | libssh +2 | 0.9.6-13.el8_8.2 | RHSA-2026:20610 |
| RHEL 8.8 E4S | libssh +2 | 0.9.6-13.el8_8.2 | RHSA-2026:20610 |
| RHEL 8.6 EUS Long Life | libssh +2 | 0.9.6-4.el8_6.2 | RHSA-2026:25911 |
| RHEL 8.6 AUS | libssh +2 | 0.9.6-4.el8_6.2 | RHSA-2026:25911 |
| RHEL 8.4 EUS Long Life | libssh +2 | 0.9.4-2.el8_4.2 | RHSA-2026:24349 |
| RHEL 8.4 AUS | libssh +2 | 0.9.4-2.el8_4.2 | RHSA-2026:24349 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 8 | libssh +2 | 0.9.6-16.el8_10 | ALSA-2025:21977 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 8 | libssh | 0.9.6-16.el8_10 | RLSA-2025:21977 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | libssh | 0.9.8-150600.11.3.1 | SUSE-SU-2025:02229-1 |
| SLES 15 SP6 | libssh | 0.9.8-150600.11.3.1 | SUSE-SU-2025:02229-1 |
| SLES 15 SP5 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SLES 15 SP4 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SLES 15 SP3 | libssh | 0.9.8-150200.13.9.1 | SUSE-SU-2025:02279-1 |
Show 17 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP5 | libssh | 0.9.8-3.15.1 | SUSE-SU-2025:02281-1 |
| SLES for SAP 15 SP5 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SLES for SAP 15 SP4 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SLES for SAP 15 SP3 | libssh | 0.9.8-150200.13.9.1 | SUSE-SU-2025:02279-1 |
| SLE Micro 6.1 | libssh | 0.10.6-slfo.1.1_2.1 | SUSE-SU-2025:20596-1 |
| SLE Micro 6.0 | libssh | 0.10.6-2.1 | SUSE-SU-2025:20557-1 |
| SLE Micro 5.5 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SLE Micro 5.4 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SLE Micro 5.3 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SLE Micro 5.2 | libssh | 0.9.8-150200.13.9.1 | SUSE-SU-2025:02279-1 |
| SLE Micro 5.1 | libssh | 0.9.8-150200.13.9.1 | SUSE-SU-2025:02279-1 |
| SLE HPC 15 SP5 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SLE HPC 15 SP4 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SLE HPC 15 SP3 | libssh | 0.9.8-150200.13.9.1 | SUSE-SU-2025:02279-1 |
| SUSE Manager Server 4.3 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SUSE Manager Proxy 4.3 | libssh | 0.9.8-150400.3.9.1 | SUSE-SU-2025:02278-1 |
| SUSE Enterprise Storage 7.1 | libssh | 0.9.8-150200.13.9.1 | SUSE-SU-2025:02279-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | libssh | 0.11.2-1.1 | openSUSE-SU-2025:15243-1 |
| openSUSE Leap 15.6 | libssh | 0.9.8-150600.11.3.1 | SUSE-SU-2025:02229-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | libssh | 0.11.2-r0 | — |
| Alpine v3.23 | libssh | 0.11.2-r0 | — |
| Alpine v3.22 | libssh | 0.11.2-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | libssh | 0.10.6-2 | — |
| Azure Linux 2 (CBL-Mariner) | libssh | 0.10.6-2 | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 8 | libssh +2 | 0.9.6-16.el8_10 | ELSA-2025-21977 |
Advisories 22
- ALSA-2025:21977 Moderate: libssh security update AlmaLinux Security Advisories · Oct 29, 2026
- USN-7619-1 libssh vulnerabilities Ubuntu Security Notices (USN) · Oct 27, 2026
- WID-SEC-2025-1423 libssh: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 13, 2026
- WID-SEC-2026-0783 IBM QRadar SIEM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 17, 2026
- RHSA-2026:25911 Red Hat Security Advisory: libssh security update Red Hat Security Advisories (RHSA) · Sep 2, 2026
- RHSA-2026:24349 Red Hat Security Advisory: libssh security update Red Hat Security Advisories (RHSA) · Sep 2, 2026
- RHSA-2026:20610 Red Hat Security Advisory: libssh security update Red Hat Security Advisories (RHSA) · Sep 2, 2026
- RHSA-2025:23024 Red Hat Security Advisory: libssh security update Red Hat Security Advisories (RHSA) · Sep 2, 2026
- RHSA-2025:21977 Red Hat Security Advisory: libssh security update Red Hat Security Advisories (RHSA) · Sep 2, 2026
- WID-SEC-2026-1118 Dell PowerProtect Data Domain OS: Mehrere Schwachstellen BSI CERT-Bund (WID) · Aug 5, 2026
- WID-SEC-2026-1194 Oracle Communications: Mehrere Schwachstellen BSI CERT-Bund (WID) · Apr 21, 2026
- openSUSE-SU-2025:15243-1 libssh-config-0.11.2-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:20596-1 Security update for libssh SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:02281-1 Security update for libssh SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:20557-1 Security update for libssh SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:02279-1 Security update for libssh SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:02229-1 Security update for libssh SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:02278-1 Security update for libssh SUSE / openSUSE Security Updates · Mar 23, 2026
- WID-SEC-2026-0165 Oracle Siebel CRM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jan 20, 2026
- DLA-4385-1 libssh - security update Debian Security (DSA / DLA) · Nov 27, 2025
- RLSA-2025:21977 Moderate: libssh security update Rocky Linux Security Advisories · Nov 25, 2025
- ELSA-2025-21977 Moderate: libssh security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Nov 24, 2025
References
- RHSA-2025:21977 vendor-advisory
- RHSA-2025:23024 vendor-advisory
- RHSA-2026:20610 vendor-advisory
- RHSA-2026:24349 vendor-advisory
- RHSA-2026:25911 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2025-5372 vdb-entry
- RHBZ#2369388 issue-tracking