HighCVE-2025-5372

    Libssh: incorrect return code handling in ssh_kdf() in libssh (CVE-2025-5372)

    Published Last modified Sources: Debian LTS, BSI, CVE.org, EUVD, Msrc Update Guide

    What is affected, what to do

    A flaw was found in libssh versions built with OpenSSL versions older than 3.0, specifically in the ssh_kdf() function responsible for key derivation. Due to inconsistent interpretation of return values where OpenSSL uses 0 to indicate failure and libssh uses 0 for success—the function may mistakenly return a success status even when key derivation fails.

    Update Libssh to version 0.11.2, Red Hat Enterprise Linux 8 to version 0:0.9.6-16.el8_10, Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support to version 0:0.9.4-2.el8_4.2.

    Affected
    • Libssh lt *..0.11.2
    • Red Hat Enterprise Linux 8 lt *..0:0.9.6-16.el8_10
    • Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support lt *..0:0.9.4-2.el8_4.2
    • Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On lt *..0:0.9.4-2.el8_4.2
    • Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support lt *..0:0.9.6-4.el8_6.2
    • Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On lt *..0:0.9.6-4.el8_6.2
    • Red Hat Enterprise Linux 8.8 Telecommunications Update Service lt *..0:0.9.6-13.el8_8.2
    • Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions lt *..0:0.9.6-13.el8_8.2
    • Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions lt *..0:0.9.6-3.el9_0.2
    Fixed in
    • Libssh 0.11.2
    • Red Hat Enterprise Linux 8 0:0.9.6-16.el8_10
    • Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support 0:0.9.4-2.el8_4.2
    • Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On 0:0.9.4-2.el8_4.2
    • Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support 0:0.9.6-4.el8_6.2
    • Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On 0:0.9.6-4.el8_6.2
    • Red Hat Enterprise Linux 8.8 Telecommunications Update Service 0:0.9.6-13.el8_8.2
    • Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions 0:0.9.6-13.el8_8.2
    • Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions 0:0.9.6-3.el9_0.2

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    8.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    5.0

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: Debian LTS, BSI, CVE.org, EUVD, Msrc Update Guide

    0.5 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 42.7

    Show all metrics
    Severity
    High
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    49.33 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    8.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    5.0
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

    Read in glossary
    0.5 %
    Low — model estimates < 1% exploitation likelihood.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    42.7
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-682

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    A flaw was found in libssh versions built with OpenSSL versions older than 3.0, specifically in the ssh_kdf() function responsible for key derivation. Due to inconsistent interpretation of return values where OpenSSL uses 0 to indicate failure and libssh uses 0 for success—the function may mistakenly return a success status even when key derivation fails. This results in uninitialized cryptographic key buffers being used in subsequent communication, potentially compromising SSH sessions' confidentiality, integrity, and availability.

    Source: Debian LTS Advisories, BSI WID Portal, BSI CSAF, cvelistv5, NVD (NIST), CVE.org (MITRE), ENISA EUVD, Microsoft Security Update Guide

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    libsshlibssh
    • < 0.11.2
    • < 0.11.2
    • 0.11.2
    • 0.11.2
    Red HatRed Hat Enterprise Linux 10
    • —
    • —
    Red HatRed Hat Enterprise Linux 6
    • —
    • —
    Red HatRed Hat Enterprise Linux 7
    • —
    • —
    Red HatRed Hat Enterprise Linux 8
    • < 0:0.9.6-16.el8_10
    • 0:0.9.6-16.el8_10
    Red HatRed Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
    • < 0:0.9.4-2.el8_4.2
    • 0:0.9.4-2.el8_4.2
    Red HatRed Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On
    • < 0:0.9.4-2.el8_4.2
    • 0:0.9.4-2.el8_4.2
    Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support
    • < 0:0.9.6-4.el8_6.2
    • 0:0.9.6-4.el8_6.2
    Red HatRed Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
    • < 0:0.9.6-4.el8_6.2
    • 0:0.9.6-4.el8_6.2
    Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Service
    • < 0:0.9.6-13.el8_8.2
    • 0:0.9.6-13.el8_8.2
    Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutions
    • < 0:0.9.6-13.el8_8.2
    • 0:0.9.6-13.el8_8.2
    Red HatRed Hat Enterprise Linux 9
    • —
    • —
    Red HatRed Hat Enterprise Linux 9.0 Update Services for SAP Solutions
    • < 0:0.9.6-3.el9_0.2
    • 0:0.9.6-3.el9_0.2
    Red HatRed Hat OpenShift Container Platform 4
    • —
    • —
    redhatopenshift_container_platform
    • 4.0
    • —
    DellPowerProtect Data Domain OS
    • < 8.3.1.20
    • < 8.3.1.30
    • < 8.7.0.1
    • < 7.13.1.60
    • < 7.13.1.70
    • < 8.6.0.0
    • < 8.7.0.0
    • 8.3.1.20
    • 8.3.1.30
    • 8.7.0.1
    • 7.13.1.60
    • 7.13.1.70
    • 8.6.0.0
    • 8.7.0.0
    IBMQRadar SIEM
    • <7.5.0 UP15
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxredhatenterprise_linux10.0
    Linuxredhatenterprise_linux6.0
    Linuxredhatenterprise_linux7.0
    Linuxredhatenterprise_linux8.0
    Linuxredhatenterprise_linux9.0
    Linuxdebianlibsshbullseye

    Weakness classes (CWE)

    • CWE-682Incorrect Calculation

      Pillar

      The product performs a calculation that generates incorrect or unintended results that are later used in security-critical decisions or resource management.

      Entry at MITRE CWE-682

    References & sources

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. Record modifiedRed Hat

      Show 17 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2025/5xxx/CVE-2025-5372.json">CVE-2025-5372</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:21977
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:23024
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:20610
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:24349
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:25911
      Referenceadded
      —
      https://access.redhat.com/security/cve/CVE-2025-5372
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=2369388
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:21977
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:23024
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:20610
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:24349
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:25911
      —
      Referenceremoved
      https://access.redhat.com/security/cve/CVE-2025-5372
      —
      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2369388
      —
      Reference typeremoved
      https://access.redhat.com/security/cve/CVE-2025-5372 Types: Third Party Advisory
      —
      Reference typeremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2369388 Types: Issue Tracking, Third Party Advisory
      —

      Source identifier: secalert@redhat.com

    2. Record modifiedRed Hat

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      libssh, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 8 (+12)
      libssh, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 8 (+12)

      Source identifier: secalert@redhat.com

    3. Record modifiedRed Hat

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:25911

      Source identifier: secalert@redhat.com

    4. Record modifiedRed Hat

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:24349

      Source identifier: secalert@redhat.com

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