There's a vulnerability in the libssh package where when a libssh consumer passes in an unexpectedly large input buffer to ssh_get_fingerprint_hash() function. In such cases the bin_to_base64() function can experience an integer overflow leading to a memory under allocation, when that happens it's possible that the program perform out of bounds write leading to a heap corruption. This issue affects only 32-bits builds of libssh.
CVE-2025-4877
MEDIUMNVD 4.54.5—
EchelonGraph scoreMEDIUM confidence
Score 4.5 from GitHub Security Advisory published 2025-08-20. NVD baseline CVSS 4.5; sources differ by 0.0.
Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
4.5
- CVSS v3
- 4.5
- EG Score
- 4.5(medium)
- EPSS
- 10.9%
- KEV
- Not listed
Published
August 20, 2025
Last Modified
May 19, 2026
References (5)
- secalert@redhathttps://access.redhat.com/errata/RHSA-2026:18683
- secalert@redhathttps://access.redhat.com/security/cve/CVE-2025-4877
- secalert@redhathttps://bugzilla.redhat.com/show_bug.cgi?id=2376193
- secalert@redhathttps://git.libssh.org/projects/libssh.git/commit/?h=stable-0.11&id=6fd9cc8ce3958092a1aae11f1f2e911b2747732d
- secalert@redhathttps://www.libssh.org/security/advisories/CVE-2025-4877.txt
Frequently asked(5)
What is CVE-2025-4877?
CVE-2025-4877 is a medium vulnerability published on August 20, 2025. There's a vulnerability in the libssh package where when a libssh consumer passes in an unexpectedly large input buffer to sshgetfingerprinthash() function. In such cases the binto_base64() function can experience an integer overflow leading to a memory under allocation, when that happens it's…
When was CVE-2025-4877 disclosed?
CVE-2025-4877 was first published in the National Vulnerability Database on August 20, 2025, with the most recent update on May 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-4877 actively exploited?
CVE-2025-4877 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 10.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-4877?
CVE-2025-4877 has a CVSS v3 base score of 4.5 (NVD).
How do I remediate CVE-2025-4877?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-4877, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2025-4877
Is Your Infrastructure Affected by CVE-2025-4877?
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