Libssh: memory exhaustion via repeated key exchange in libssh
CVE-2025-8277 is fixed in 7 products on 1 platform, first by DEBIAN-CVE-2025-8277, released September 9, 2025. It is not reported as exploited. Patch Radar priority: Routine.
A flaw was found in libssh's handling of key exchange (KEX) processes when a client repeatedly sends incorrect KEX guesses. The library fails to free memory during these rekey operations, which can gradually exhaust system memory. This issue can lead to crashes on the client side, particularly when using libgcrypt, which impacts application stability and availability.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| libssh · Debian 12.15 (bookworm) | 0.10.6-0+deb12u2 | DEBIAN-CVE-2025-8277 | Sep 9, 2025 |
| libssh · Debian 13.5 (trixie) | 0.11.2-1+deb13u1 | DEBIAN-CVE-2025-8277 | Sep 9, 2025 |
| libssh · Debian 14 | 0.11.3-1 | DEBIAN-CVE-2025-8277 | Sep 9, 2025 |
| libssh · RHEL 9 | 0:0.10.4-18.el9 | RHSA-2026:18683 | May 27, 2026 |
| libssh · almalinux 9 | 0.10.4-18.el9 | ALSA-2026:18683 | May 19, 2026 |
| libssh · amzn 2023 | 0.10.6-1.amzn2023.0.3 | ALAS2023-2025-1264 | Nov 10, 2025 |
| libssh · ol 9 | 0:0.10.4-18.el9 | ELSA-2026-18683 | Jun 12, 2026 |
| libssh · opensuse-leap 15.6 | 0.9.8-150600.11.6.1 | SUSE-SU-2025:03369-1 | Sep 26, 2025 |
| libssh · rocky 9 | 0:0.10.4-18.el9 | RLSA-2026:18683 | May 28, 2026 |
| libssh · sles 15.6 | 0.9.8-150600.11.6.1 | SUSE-SU-2025:03369-1 | Sep 26, 2025 |
| libssh · sles 15.7 | 0.9.8-150600.11.6.1 | SUSE-SU-2025:03369-1 | Sep 26, 2025 |
| libssh-4 · Ubuntu 18.04.6 LTS (bionic) | 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6 | libssh-4 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6 | Mar 12, 2026 |
| libssh-4 · Ubuntu 20.04 LTS (focal) | 0.9.3-2ubuntu2.5+esm3 | libssh-4 0.9.3-2ubuntu2.5+esm3 | Mar 12, 2026 |
| libssh-4 · Ubuntu 22.04.1 LTS (jammy) | 0.9.6-2ubuntu0.22.04.6 | libssh-4 0.9.6-2ubuntu0.22.04.6 | Mar 12, 2026 |
| libssh-4 · Ubuntu 24.04.5 LTS (noble) | 0.10.6-2ubuntu0.3 | libssh-4 0.10.6-2ubuntu0.3 | Mar 12, 2026 |
| libssh-4 · Ubuntu 25.10 (questing) | 0.11.2-1ubuntu0.2 | libssh-4 0.11.2-1ubuntu0.2 | Mar 12, 2026 |
| libssh-config · RHEL 9 | 0:0.10.4-18.el9 | RHSA-2026:18683 | May 27, 2026 |
| libssh-config · almalinux 9 | 0.10.4-18.el9 | ALSA-2026:18683 | May 19, 2026 |
| libssh-config · amzn 2023 | 0.10.6-1.amzn2023.0.3 | ALAS2023-2025-1264 | Nov 10, 2025 |
| libssh-config · ol 9 | 0:0.10.4-18.el9 | ELSA-2026-18683 | Jun 12, 2026 |
| libssh-debuginfo · amzn 2023 | 0.10.6-1.amzn2023.0.3 | ALAS2023-2025-1264 | Nov 10, 2025 |
| libssh-debugsource · amzn 2023 | 0.10.6-1.amzn2023.0.3 | ALAS2023-2025-1264 | Nov 10, 2025 |
| libssh-devel · RHEL 9 | 0:0.10.4-18.el9 | RHSA-2026:18683 | May 27, 2026 |
| libssh-devel · almalinux 9 | 0.10.4-18.el9 | ALSA-2026:18683 | May 19, 2026 |
| libssh-devel · amzn 2023 | 0.10.6-1.amzn2023.0.3 | ALAS2023-2025-1264 | Nov 10, 2025 |
| libssh-devel · ol 9 | 0:0.10.4-18.el9 | ELSA-2026-18683 | Jun 12, 2026 |
| libssh-gcrypt-4 · Ubuntu 18.04.6 LTS (bionic) | 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6 | libssh-gcrypt-4 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6 | Mar 12, 2026 |
| libssh-gcrypt-4 · Ubuntu 20.04 LTS (focal) | 0.9.3-2ubuntu2.5+esm3 | libssh-gcrypt-4 0.9.3-2ubuntu2.5+esm3 | Mar 12, 2026 |
| libssh-gcrypt-4 · Ubuntu 22.04.1 LTS (jammy) | 0.9.6-2ubuntu0.22.04.6 | libssh-gcrypt-4 0.9.6-2ubuntu0.22.04.6 | Mar 12, 2026 |
| libssh-gcrypt-4 · Ubuntu 24.04.5 LTS (noble) | 0.10.6-2ubuntu0.3 | libssh-gcrypt-4 0.10.6-2ubuntu0.3 | Mar 12, 2026 |
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