CVE-2025-4877

MEDIUMPre-NVD 4.54.5—
EchelonGraph scoreMEDIUM confidence

Score 4.5 from GitHub Security Advisory published 2025-08-20. a secondary CVSS source baseline 4.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
4.5
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 4.5Exploit: NoneExposed: 0

A fix is available — apply it.

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.

CVSS v3
4.5
EG Score
4.5(medium)
EG Risk
20(Track)
EG Risk 20/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity45% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
9.0%
KEV
Not listed

Published

August 20, 2025

Last Modified

June 30, 2026

Advisory Details (5)

Auto-updated Jun 27, 2026
Patch available. Sources: redhat.
generic
https://www.libssh.org/security/advisories/CVE-2025-4877.txt
generic

projects/libssh.git - libssh shared repository

https://git.libssh.org/projects/libssh.git/commit/?h=stable-0.11&id=6fd9cc8ce3958092a1aae11f1f2e911b2747732d
redhat Patch Available

2376193 – (CVE-2025-4877) CVE-2025-4877 libssh: Write beyond bounds in binary to base64 conversion functions

Affected: Red Hat Enterprise Linux 9

https://bugzilla.redhat.com/show_bug.cgi?id=2376193
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2025-4877
redhat Patch Available

Affected: Red Hat Enterprise Linux 9.

https://access.redhat.com/errata/RHSA-2026:18683

Vendor Advisories for CVE-2025-4877(2)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibssh-doc (0.11.1-1ubuntu0.1) @ plucky2026-05-21ubuntu
ubuntulibssh-gcrypt-dev (0.8.0~20170825.94fa1e38-1ubuntu0.7+esm4) @ bionic2026-05-21ubuntu
redhatlibssh-0:0.10.4-18.el92026-05-19redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Additional Vendor Advisories

(3)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 11× in last 7d / 49× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 132 total refreshes for this CVE.

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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 June 30, 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 9.0% 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.

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