Libssh: write beyond bounds in binary to base64 conversion functions

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Summary

CVECVE-2025-4877
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2025-08-20 13:15:28 UTC
Updated2026-05-19 14:16:28 UTC
DescriptionThere'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.

Risk And Classification

Primary CVSS: v3.1 4.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

EPSS: 0.000350000 probability, percentile 0.106030000 (date 2026-05-26)

Problem Types: CWE-787 | CWE-787 Out-of-bounds Write

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary4.5MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
3.1CNACVSS4.5MEDIUMCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Enterprise Linux 9 unaffected 0:0.10.4-18.el9 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 9 unaffected 0:0.10.4-18.el9 * rpm Not specified
CNA Red Hat Red Hat Enterprise Linux 10 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
CNA Red Hat Red Hat OpenShift Container Platform 4 Not specified Not specified

References

ReferenceSourceLinkTags
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
www.libssh.org/security/advisories/CVE-2025-4877.txt [email protected] www.libssh.org
git.libssh.org/projects/libssh.git/commit [email protected] git.libssh.org
access.redhat.com/errata/RHSA-2026:18683 [email protected] access.redhat.com
access.redhat.com/security/cve/CVE-2025-4877 [email protected] access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
CNA2025-07-03T18:04:11.051ZReported to Red Hat.
CNA2025-06-24T00:00:00.000ZMade public.
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