HighCVE-2025-5987

    Libssh: invalid return code for chacha20 poly1305 with openssl backend (CVE-2025-5987)

    Published Last modified Sources: Red Hat, CVE.org, Msrc Update Guide, BSI

    What is affected, what to do

    A flaw was found in libssh when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context.

    Update Libssh to version 0.11.2, Red Hat Enterprise Linux 10 to version 0:0.11.1-5.el10_1, Red Hat Enterprise Linux 10.0 Extended Update Support to version 0:0.11.1-4.el10_0.1.

    Affected
    • Libssh lt 0.10.0..0.11.2
    • Red Hat Enterprise Linux 10 lt *..0:0.11.1-5.el10_1
    • Red Hat Enterprise Linux 10.0 Extended Update Support lt *..0:0.11.1-4.el10_0.1
    • Red Hat Enterprise Linux 9 lt *..0:0.10.4-17.el9_7
    • Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions lt *..0:0.10.4-9.el9_2.2
    • Red Hat Enterprise Linux 9.4 Extended Update Support lt *..0:0.10.4-13.el9_4.2
    • Red Hat Enterprise Linux 9.6 Extended Update Support lt *..0:0.10.4-15.el9_6.1
    • Red Hat OpenShift Container Platform 4.13 lt *..413.92.202602240113-0
    • Red Hat OpenShift Container Platform 4.14 lt *..414.92.202601191325-0
    • Red Hat OpenShift Container Platform 4.15 lt *..415.92.202601271320-0
    • Red Hat OpenShift Container Platform 4.16 lt *..416.94.202601160124-0
    • Red Hat OpenShift Container Platform 4.17 lt *..417.94.202601120213-0
    • Red Hat OpenShift Container Platform 4.18 lt *..418.94.202601202224-0
    • Red Hat OpenShift Container Platform 4.19 lt *..4.19.9.6.202601260820-0
    • Red Hat OpenShift Container Platform 4.20 lt *..4.20.9.6.202601211057-0
    Fixed in
    • Libssh 0.11.2
    • Red Hat Enterprise Linux 10 0:0.11.1-5.el10_1
    • Red Hat Enterprise Linux 10.0 Extended Update Support 0:0.11.1-4.el10_0.1
    • Red Hat Enterprise Linux 9 0:0.10.4-17.el9_7
    • Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions 0:0.10.4-9.el9_2.2
    • Red Hat Enterprise Linux 9.4 Extended Update Support 0:0.10.4-13.el9_4.2
    • Red Hat Enterprise Linux 9.6 Extended Update Support 0:0.10.4-15.el9_6.1
    • Red Hat OpenShift Container Platform 4.13 413.92.202602240113-0
    • Red Hat OpenShift Container Platform 4.14 414.92.202601191325-0
    • Red Hat OpenShift Container Platform 4.15 415.92.202601271320-0
    • Red Hat OpenShift Container Platform 4.16 416.94.202601160124-0
    • Red Hat OpenShift Container Platform 4.17 417.94.202601120213-0
    • Red Hat OpenShift Container Platform 4.18 418.94.202601202224-0
    • Red Hat OpenShift Container Platform 4.19 4.19.9.6.202601260820-0
    • Red Hat OpenShift Container Platform 4.20 4.20.9.6.202601211057-0

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

    Metrics

    8.1

    Priority

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

    Source: NVD, CVSS v3

    8.1

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: Red Hat, CVE.org, Msrc Update Guide, BSI

    1.7 %

    EPSS score

    Moderate — model estimates 1-10% exploitation likelihood.

    Source: FIRST EPSS, percentile 77.5

    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
    98.30 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
    8.1 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
    8.1
    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
    1.7 %
    Moderate — model estimates 1-10% 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
    77.5
    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-393

    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 when using the ChaCha20 cipher with the OpenSSL library. If an attacker manages to exhaust the heap space, this error is not detected and may lead to libssh using a partially initialized cipher context. This occurs because the OpenSSL error code returned aliases with the SSH_OK code, resulting in libssh not properly detecting the error returned by the OpenSSL library. This issue can lead to undefined behavior, including compromised data confidentiality and integrity or crashes.

    Source: redhat_csaf, NVD (NIST), Microsoft Security Update Guide, CVE.org (MITRE), cvelistv5, BSI WID Portal, BSI CSAF

    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
    —libssh
    • 0.10.0 – < 0.11.2
    • 0.11.2
    Red HatRed Hat Enterprise Linux 10
    • < 0:0.11.1-5.el10_1
    • 0:0.11.1-5.el10_1
    Red HatRed Hat Enterprise Linux 10.0 Extended Update Support
    • < 0:0.11.1-4.el10_0.1
    • 0:0.11.1-4.el10_0.1
    Red HatRed Hat Enterprise Linux 6
    • —
    • —
    Red HatRed Hat Enterprise Linux 7
    • —
    • —
    Red HatRed Hat Enterprise Linux 8
    • —
    • —
    Red HatRed Hat Enterprise Linux 9
    • < 0:0.10.4-17.el9_7
    • 0:0.10.4-17.el9_7
    Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP Solutions
    • < 0:0.10.4-9.el9_2.2
    • 0:0.10.4-9.el9_2.2
    Red HatRed Hat Enterprise Linux 9.4 Extended Update Support
    • < 0:0.10.4-13.el9_4.2
    • 0:0.10.4-13.el9_4.2
    Red HatRed Hat Enterprise Linux 9.6 Extended Update Support
    • < 0:0.10.4-15.el9_6.1
    • 0:0.10.4-15.el9_6.1
    Red HatRed Hat OpenShift Container Platform 4
    • —
    • —
    Red HatRed Hat OpenShift Container Platform 4.13
    • < 413.92.202602240113-0
    • 413.92.202602240113-0
    Red HatRed Hat OpenShift Container Platform 4.14
    • < 414.92.202601191325-0
    • 414.92.202601191325-0
    Red HatRed Hat OpenShift Container Platform 4.15
    • < 415.92.202601271320-0
    • 415.92.202601271320-0
    Red HatRed Hat OpenShift Container Platform 4.16
    • < 416.94.202601160124-0
    • 416.94.202601160124-0
    Red HatRed Hat OpenShift Container Platform 4.17
    • < 417.94.202601120213-0
    • 417.94.202601120213-0
    Red HatRed Hat OpenShift Container Platform 4.18
    • < 418.94.202601202224-0
    • 418.94.202601202224-0
    Red HatRed Hat OpenShift Container Platform 4.19
    • < 4.19.9.6.202601260820-0
    • 4.19.9.6.202601260820-0
    Red HatRed Hat OpenShift Container Platform 4.20
    • < 4.20.9.6.202601211057-0
    • 4.20.9.6.202601211057-0
    libsshlibssh
    • 0.10.0 – < 0.11.2
    • 0.11.2

    Vendors and products

    Weakness classes (CWE)

    • CWE-393Return of Wrong Status Code

      Base

      A function or operation returns an incorrect return value or status code that does not indicate the true result of execution, causing the product to modify its behavior based on the incorrect result.

      Entry at MITRE CWE-393

    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

      1 individual change: Affected versions (publisher)

      Show the original change
      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-2025-5987.json">CVE-2025-5987</a>

      Source identifier: secalert@redhat.com

    2. Record modifiedRed Hat

      Show 37 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-2025-5987.json">CVE-2025-5987</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:23483
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2025:23484
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:0427
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:0428
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:0430
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:0431
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:0702
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:0978
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:0980
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:0985
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:0996
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:1539
      Referenceadded
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      https://access.redhat.com/errata/RHSA-2026:1541
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:3415
      Referenceadded
      —
      https://access.redhat.com/security/cve/CVE-2025-5987
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=2376219
      Referenceadded
      —
      https://www.libssh.org/security/advisories/CVE-2025-5987.txt
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:23483
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2025:23484
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:0427
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:0428
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:0430
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:0431
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:0702
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:0978
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:0980
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:0985
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:0996
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:1539
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:1541
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:3415
      —
      Referenceremoved
      https://access.redhat.com/security/cve/CVE-2025-5987
      —
      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2376219
      —
      Referenceremoved
      https://www.libssh.org/security/advisories/CVE-2025-5987.txt
      —
      Reference typeremoved
      https://access.redhat.com/security/cve/CVE-2025-5987 Types: Third Party Advisory
      —
      Reference typeremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2376219 Types: Issue Tracking, Third Party Advisory
      —

      Source identifier: secalert@redhat.com

    3. 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
      …, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support (+17)
      …, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support (+16)

      Source identifier: secalert@redhat.com

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