# CVE-2025-4877: Libssh: write beyond bounds in binary to base64 conversion functions CVE-2025-4877 is fixed in 5 products on 1 platform, first by libssh-4 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm4, released June 24, 2025. It is not reported as exploited. Patch Radar priority: Routine. - Web page: https://patchblox.com/security/cve/CVE-2025-4877 - Priority: Routine - CVSS: 6.5 (Medium) - EPSS: 0.0020 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Jun 24, 2025 - Weakness: Out-of-bounds Write - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-4877 ## Description There's a vulnerability in the libssh package where when a libssh consumerpasses in an unexpectedly large input buffer to ssh_get_fingerprint_hash()function. In such cases the bin_to_base64() function can experience aninteger overflow leading to a memory under allocation, when that happensit's possible that the program perform out of bounds write leading to aheap corruption.This issue affects only 32-bits builds of libssh. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | libssh Debian 11.6 (bullseye) | 0.9.8-0+deb11u2 | [DLA-4385-1](https://patchblox.com/security/data/fix/linux/dla-4385-1.md) | Nov 27, 2025 | | Linux | libssh Debian 12.15 (bookworm) | 0.10.6-0+deb12u2 | [DEBIAN-CVE-2025-4877](https://patchblox.com/security/data/fix/linux/debian-cve-2025-4877.md) | Aug 20, 2025 | | Linux | libssh Debian 13.5 (trixie) | 0.11.2-1 | [DEBIAN-CVE-2025-4877](https://patchblox.com/security/data/fix/linux/debian-cve-2025-4877.md) | Aug 20, 2025 | | Linux | libssh Debian 14 | 0.11.2-1 | [DEBIAN-CVE-2025-4877](https://patchblox.com/security/data/fix/linux/debian-cve-2025-4877.md) | Aug 20, 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 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 | 0.9.8-150600.11.3.1 | [SUSE-SU-2025:02229-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-02229-1.md) | Jul 4, 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 | 0.9.8-150600.11.3.1 | [SUSE-SU-2025:02229-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-02229-1.md) | Jul 4, 2025 | | Linux | libssh sles 15.7 | 0.9.8-150600.11.3.1 | [SUSE-SU-2025:02229-1](https://patchblox.com/security/data/fix/linux/suse-su-2025-02229-1.md) | Jul 4, 2025 | | Linux | libssh-4 Ubuntu 18.04.6 LTS (bionic) | 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm4 | [libssh-4 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssh-4-0.8.0-20170825.94fa1e38-1ubuntu0.7-esm4.md) | Jun 24, 2025 | | Linux | libssh-4 Ubuntu 20.04 LTS (focal) | 0.9.3-2ubuntu2.5+esm1 | [libssh-4 0.9.3-2ubuntu2.5+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libssh-4-0.9.3-2ubuntu2.5-esm1.md) | Jun 24, 2025 | | Linux | libssh-4 Ubuntu 22.04.1 LTS (jammy) | 0.9.6-2ubuntu0.22.04.4 | [libssh-4 0.9.6-2ubuntu0.22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libssh-4-0.9.6-2ubuntu0.22.04.4.md) | Jun 24, 2025 | | Linux | libssh-4 Ubuntu 24.04.5 LTS (noble) | 0.10.6-2ubuntu0.1 | [libssh-4 0.10.6-2ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libssh-4-0.10.6-2ubuntu0.1.md) | Jun 24, 2025 | | Linux | libssh-4 Ubuntu 24.10 (oracular) | 0.10.6-3ubuntu1.1 | [libssh-4 0.10.6-3ubuntu1.1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libssh-4-0.10.6-3ubuntu1.1.md) | Jun 25, 2025 | | Linux | libssh-4 Ubuntu 25.04 (plucky) | 0.11.1-1ubuntu0.1 | [libssh-4 0.11.1-1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-libssh-4-0.11.1-1ubuntu0.1.md) | Jun 25, 2025 | | 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 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-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 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+esm4 | [libssh-gcrypt-4 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm4](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssh-gcrypt-4-0.8.0-20170825.94fa1e38-1ubuntu0.7-esm4.md) | Jun 24, 2025 | | Linux | libssh-gcrypt-4 Ubuntu 20.04 LTS (focal) | 0.9.3-2ubuntu2.5+esm1 | [libssh-gcrypt-4 0.9.3-2ubuntu2.5+esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libssh-gcrypt-4-0.9.3-2ubuntu2.5-esm1.md) | Jun 24, 2025 | | Linux | libssh-gcrypt-4 Ubuntu 22.04.1 LTS (jammy) | 0.9.6-2ubuntu0.22.04.4 | [libssh-gcrypt-4 0.9.6-2ubuntu0.22.04.4](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libssh-gcrypt-4-0.9.6-2ubuntu0.22.04.4.md) | Jun 24, 2025 | | Linux | libssh-gcrypt-4 Ubuntu 24.04.5 LTS (noble) | 0.10.6-2ubuntu0.1 | [libssh-gcrypt-4 0.10.6-2ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libssh-gcrypt-4-0.10.6-2ubuntu0.1.md) | Jun 24, 2025 | | Linux | libssh-gcrypt-4 Ubuntu 24.10 (oracular) | 0.10.6-3ubuntu1.1 | [libssh-gcrypt-4 0.10.6-3ubuntu1.1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libssh-gcrypt-4-0.10.6-3ubuntu1.1.md) | Jun 25, 2025 | --- Data as of 2026-11-08T00:53:09Z UTC. 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