# CVE-2025-8277: 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. - Web page: https://patchblox.com/security/cve/CVE-2025-8277 - Priority: Routine - CVSS: 6.5 (low) - EPSS: 0.0043 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Sep 9, 2025 - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-8277 ## Description 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 | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | libssh Debian 12.15 (bookworm) | 0.10.6-0+deb12u2 | [DEBIAN-CVE-2025-8277](https://patchblox.com/security/data/fix/linux/debian-cve-2025-8277.md) | Sep 9, 2025 | | Linux | libssh Debian 13.5 (trixie) | 0.11.2-1+deb13u1 | [DEBIAN-CVE-2025-8277](https://patchblox.com/security/data/fix/linux/debian-cve-2025-8277.md) | Sep 9, 2025 | | Linux | libssh Debian 14 | 0.11.3-1 | [DEBIAN-CVE-2025-8277](https://patchblox.com/security/data/fix/linux/debian-cve-2025-8277.md) | Sep 9, 2025 | | Linux | libssh RHEL 9 | 0:0.10.4-18.el9 | [RHSA-2026:18683](https://patchblox.com/security/data/fix/linux/rhsa-2026-18683.md) | May 27, 2026 | | Linux | libssh almalinux 9 | 0.10.4-18.el9 | [ALSA-2026:18683](https://patchblox.com/security/data/fix/linux/alsa-2026-18683.md) | May 19, 2026 | | Linux | libssh amzn 2023 | 0.10.6-1.amzn2023.0.3 | [ALAS2023-2025-1264](https://patchblox.com/security/data/fix/linux/alas2023-2025-1264.md) | Nov 10, 2025 | | Linux | libssh ol 9 | 0:0.10.4-18.el9 | [ELSA-2026-18683](https://patchblox.com/security/data/fix/linux/elsa-2026-18683.md) | Jun 12, 2026 | | Linux | libssh opensuse-leap 15.6 | 0.9.8-150600.11.6.1 | [SUSE-SU-2025:03369-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-03369-1.md) | Sep 26, 2025 | | Linux | libssh rocky 9 | 0:0.10.4-18.el9 | [RLSA-2026:18683](https://patchblox.com/security/data/fix/linux/rlsa-2026-18683.md) | May 28, 2026 | | Linux | libssh sles 15.6 | 0.9.8-150600.11.6.1 | [SUSE-SU-2025:03369-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-03369-1.md) | Sep 26, 2025 | | Linux | libssh sles 15.7 | 0.9.8-150600.11.6.1 | [SUSE-SU-2025:03369-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-03369-1.md) | Sep 26, 2025 | | Linux | 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](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssh-4-0.8.0-20170825.94fa1e38-1ubuntu0.7-esm6.md) | Mar 12, 2026 | | Linux | libssh-4 Ubuntu 20.04 LTS (focal) | 0.9.3-2ubuntu2.5+esm3 | [libssh-4 0.9.3-2ubuntu2.5+esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libssh-4-0.9.3-2ubuntu2.5-esm3.md) | Mar 12, 2026 | | Linux | libssh-4 Ubuntu 22.04.1 LTS (jammy) | 0.9.6-2ubuntu0.22.04.6 | [libssh-4 0.9.6-2ubuntu0.22.04.6](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libssh-4-0.9.6-2ubuntu0.22.04.6.md) | Mar 12, 2026 | | Linux | libssh-4 Ubuntu 24.04.5 LTS (noble) | 0.10.6-2ubuntu0.3 | [libssh-4 0.10.6-2ubuntu0.3](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libssh-4-0.10.6-2ubuntu0.3.md) | Mar 12, 2026 | | Linux | libssh-4 Ubuntu 25.10 (questing) | 0.11.2-1ubuntu0.2 | [libssh-4 0.11.2-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libssh-4-0.11.2-1ubuntu0.2.md) | Mar 12, 2026 | | Linux | libssh-config RHEL 9 | 0:0.10.4-18.el9 | [RHSA-2026:18683](https://patchblox.com/security/data/fix/linux/rhsa-2026-18683.md) | May 27, 2026 | | Linux | libssh-config almalinux 9 | 0.10.4-18.el9 | [ALSA-2026:18683](https://patchblox.com/security/data/fix/linux/alsa-2026-18683.md) | May 19, 2026 | | Linux | libssh-config amzn 2023 | 0.10.6-1.amzn2023.0.3 | [ALAS2023-2025-1264](https://patchblox.com/security/data/fix/linux/alas2023-2025-1264.md) | Nov 10, 2025 | | Linux | libssh-config ol 9 | 0:0.10.4-18.el9 | [ELSA-2026-18683](https://patchblox.com/security/data/fix/linux/elsa-2026-18683.md) | Jun 12, 2026 | | Linux | libssh-debuginfo amzn 2023 | 0.10.6-1.amzn2023.0.3 | [ALAS2023-2025-1264](https://patchblox.com/security/data/fix/linux/alas2023-2025-1264.md) | Nov 10, 2025 | | Linux | libssh-debugsource amzn 2023 | 0.10.6-1.amzn2023.0.3 | [ALAS2023-2025-1264](https://patchblox.com/security/data/fix/linux/alas2023-2025-1264.md) | Nov 10, 2025 | | Linux | libssh-devel RHEL 9 | 0:0.10.4-18.el9 | [RHSA-2026:18683](https://patchblox.com/security/data/fix/linux/rhsa-2026-18683.md) | May 27, 2026 | | Linux | libssh-devel almalinux 9 | 0.10.4-18.el9 | [ALSA-2026:18683](https://patchblox.com/security/data/fix/linux/alsa-2026-18683.md) | May 19, 2026 | | Linux | libssh-devel amzn 2023 | 0.10.6-1.amzn2023.0.3 | [ALAS2023-2025-1264](https://patchblox.com/security/data/fix/linux/alas2023-2025-1264.md) | Nov 10, 2025 | | Linux | libssh-devel ol 9 | 0:0.10.4-18.el9 | [ELSA-2026-18683](https://patchblox.com/security/data/fix/linux/elsa-2026-18683.md) | Jun 12, 2026 | | Linux | 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](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssh-gcrypt-4-0.8.0-20170825.94fa1e38-1ubuntu0.7-esm6.md) | Mar 12, 2026 | | Linux | libssh-gcrypt-4 Ubuntu 20.04 LTS (focal) | 0.9.3-2ubuntu2.5+esm3 | [libssh-gcrypt-4 0.9.3-2ubuntu2.5+esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libssh-gcrypt-4-0.9.3-2ubuntu2.5-esm3.md) | Mar 12, 2026 | | Linux | 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](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libssh-gcrypt-4-0.9.6-2ubuntu0.22.04.6.md) | Mar 12, 2026 | | Linux | libssh-gcrypt-4 Ubuntu 24.04.5 LTS (noble) | 0.10.6-2ubuntu0.3 | [libssh-gcrypt-4 0.10.6-2ubuntu0.3](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libssh-gcrypt-4-0.10.6-2ubuntu0.3.md) | Mar 12, 2026 | --- Data as of 2026-11-08T06:59:42Z UTC. 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