MediumCVE-2025-9820

    Gnutls: stack-based buffer overflow in gnutls_pkcs11_token_init() function (CVE-2025-9820)

    Published Last modified Sources: BSI, Red Hat, Siemens ProductCERT, Ubuntu, SUSE, Debian LTS, CVE.org, EUVD

    What is affected, what to do

    A flaw was found in the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer.

    Update Red Hat Enterprise Linux 10 to version 0:3.8.10-3.el10_1, Red Hat Enterprise Linux 8 to version 0:3.6.16-8.el8_10.5, Red Hat Enterprise Linux 9 to version 0:3.8.3-10.el9_7.

    Affected
    • Gnutls eq 3.8.1..3.8.1
    • Gnutls eq 3.8.2..3.8.2
    • Gnutls eq 3.8.3..3.8.3
    • Gnutls eq 3.8.4..3.8.4
    • Gnutls eq 3.8.5..3.8.5
    • Gnutls eq 3.8.6..3.8.6
    • Gnutls eq 3.8.7..3.8.7
    • Gnutls eq 3.8.8..3.8.8
    • Gnutls eq 3.8.9..3.8.9
    • Gnutls eq 3.8.10..3.8.10
    • Red Hat Enterprise Linux 10 lt *..0:3.8.10-3.el10_1
    • Red Hat Enterprise Linux 8 lt *..0:3.6.16-8.el8_10.5
    • Red Hat Enterprise Linux 9 lt *..0:3.8.3-10.el9_7
    • Red Hat RHEL-8 based Middleware Containers lt *..7.13.5-4.1777325677
    • Red Hat RHEL-8 based Middleware Containers lt *..7.13.5-4.1777325711
    • Red Hat RHEL-8 based Middleware Containers lt *..7.13.5-4.1777325710
    • Red Hat RHEL-8 based Middleware Containers lt *..7.13.5-3.1777325680
    • Red Hat RHEL-8 based Middleware Containers lt *..7.13.5-4.1777325709
    • Red Hat RHEL-8 based Middleware Containers lt *..7.13.5-4.1777325680
    • Red Hat RHEL-8 based Middleware Containers lt *..7.13.5-4.1777325708
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 lt *..1791459707
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 lt *..1791459711
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 lt *..1791459759
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 lt *..1789029076
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 lt *..1791966259
    • Red Hat Ceph Storage 8 lt *..1774002867
    • Red Hat Discovery 2 lt *..1775668717
    • Red Hat Discovery 2 lt *..1775675922
    • Red Hat Hardened Images lt *..3.8.12-1.1.hum1
    • Red Hat Insights proxy 1.5 lt *..1773685509
    • Red Hat Update Infrastructure 5 lt *..1773670073
    • Red Hat Update Infrastructure 5 lt *..1773672059
    • Red Hat Update Infrastructure 5 lt *..1773668803
    • Red Hat Update Infrastructure 5 lt *..1773670137
    Fixed in
    • Red Hat Enterprise Linux 10 0:3.8.10-3.el10_1
    • Red Hat Enterprise Linux 8 0:3.6.16-8.el8_10.5
    • Red Hat Enterprise Linux 9 0:3.8.3-10.el9_7
    • Red Hat RHEL-8 based Middleware Containers 7.13.5-4.1777325677
    • Red Hat RHEL-8 based Middleware Containers 7.13.5-4.1777325711
    • Red Hat RHEL-8 based Middleware Containers 7.13.5-4.1777325710
    • Red Hat RHEL-8 based Middleware Containers 7.13.5-3.1777325680
    • Red Hat RHEL-8 based Middleware Containers 7.13.5-4.1777325709
    • Red Hat RHEL-8 based Middleware Containers 7.13.5-4.1777325680
    • Red Hat RHEL-8 based Middleware Containers 7.13.5-4.1777325708
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 1791459707
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 1791459711
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 1791459759
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 1789029076
    • Red Hat Cert Manager support for Red Hat OpenShift release 1.18 1791966259
    • Red Hat Ceph Storage 8 1774002867
    • Red Hat Discovery 2 1775668717
    • Red Hat Discovery 2 1775675922
    • Red Hat Hardened Images 3.8.12-1.1.hum1
    • Red Hat Insights proxy 1.5 1773685509
    • Red Hat Update Infrastructure 5 1773670073
    • Red Hat Update Infrastructure 5 1773672059
    • Red Hat Update Infrastructure 5 1773668803
    • Red Hat Update Infrastructure 5 1773670137

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

    Metrics

    4.0

    Priority

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

    Source: NVD, CVSS v3

    4.0

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: BSI, Red Hat, Siemens ProductCERT, Ubuntu, SUSE, Debian LTS, CVE.org, EUVD

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 12.8

    Show all metrics
    Severity
    Medium
    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
    35.14 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
    4.0 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
    4.0
    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
    0.2 %
    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
    12.8
    Elevated — this CVE ranks above at least 10% of all CVEs scored today.
    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-121

    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
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    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 the GnuTLS library, specifically in the gnutls_pkcs11_token_init() function that handles PKCS#11 token initialization. When a token label longer than expected is processed, the function writes past the end of a fixed-size stack buffer. This programming error can cause the application using GnuTLS to crash or, in certain conditions, be exploited for code execution. As a result, systems or applications relying on GnuTLS may be vulnerable to a denial of service or local privilege escalation attacks.

    Source: BSI WID Portal, BSI CSAF, redhat_csaf, siemens_advisory, Ubuntu Security Notices, suse_csaf, Debian LTS Advisories, cvelistv5, NVD (NIST), CVE.org (MITRE), ENISA EUVD

    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
    —gnutls
    • 3.8.3
    • 3.8.9
    • 3.8.6
    • 3.8.2
    • 3.8.8
    • 3.8.10
    • 3.8.7
    • 3.8.5
    • 3.8.1
    • 3.8.4
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    Red HatCert Manager support for Red Hat OpenShift release 1.18
    • < 1791459711
    • < 1791966259
    • < 1791459707
    • < 1789029076
    • < 1791459759
    • 1791459711
    • 1791966259
    • 1791459707
    • 1789029076
    • 1791459759
    Red HatRed Hat Ceph Storage 8
    • < 1774002867
    • 1774002867
    Red HatRed Hat Discovery 2
    • < 1775668717
    • < 1775675922
    • 1775668717
    • 1775675922
    Red HatRed Hat Enterprise Linux 10
    • < 0:3.8.10-3.el10_1
    • 0:3.8.10-3.el10_1
    Red HatRed Hat Enterprise Linux 6
    • —
    • —
    Red HatRed Hat Enterprise Linux 7
    • —
    • —
    Red HatRed Hat Enterprise Linux 8
    • < 0:3.6.16-8.el8_10.5
    • 0:3.6.16-8.el8_10.5
    Red HatRed Hat Enterprise Linux 9
    • < 0:3.8.3-10.el9_7
    • 0:3.8.3-10.el9_7
    Red HatRed Hat Hardened Images
    • < 3.8.12-1.1.hum1
    • 3.8.12-1.1.hum1
    Red HatRed Hat Insights proxy 1.5
    • < 1773685509
    • 1773685509
    Red HatRed Hat OpenShift Container Platform 4
    • —
    • —
    Red HatRed Hat Update Infrastructure 5
    • < 1773670137
    • < 1773672059
    • < 1773670073
    • < 1773668803
    • 1773670137
    • 1773672059
    • 1773670073
    • 1773668803
    Red HatRHEL-8 based Middleware Containers
    • < 7.13.5-4.1777325709
    • < 7.13.5-4.1777325680
    • < 7.13.5-4.1777325677
    • < 7.13.5-4.1777325711
    • < 7.13.5-4.1777325710
    • < 7.13.5-3.1777325680
    • < 7.13.5-4.1777325708
    • 7.13.5-4.1777325709
    • 7.13.5-4.1777325680
    • 7.13.5-4.1777325677
    • 7.13.5-4.1777325711
    • 7.13.5-4.1777325710
    • 7.13.5-3.1777325680
    • 7.13.5-4.1777325708
    DellSecure Connect Gateway
    • < 5.34.00.16
    • 5.34.00.16
    IBMQRadar SIEM
    • <7.5.0 UP15 IF02
    • —
    IBMSecurity Verify Access
    • < 10.0.9.2
    • 10.0.9.2
    MeinbergLANTIME
    • < V7.10.007
    • V7.10.007
    Open SourceGnuTLS
    • < 3.8.11
    • 3.8.11
    Red HatEnterprise Linux
    • 10.0 Extended Update Support
    • —
    XeroxFreeFlow Print Server
    • v7
    • v2
    • —
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebiangnutls28bullseye
    Linuxubuntugnutls28bionic
    Linuxubuntugnutls28focal
    Linuxubuntugnutls28xenial

    Weakness classes (CWE)

    • CWE-121Stack-based Buffer Overflow

      Variant

      A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).

      Entry at MITRE CWE-121

    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 2 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/2025/9xxx/CVE-2025-9820.json">CVE-2025-9820</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:82857

      Source identifier: secalert@redhat.com

    2. Record modifiedRed Hat

      Show 4 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/2025/9xxx/CVE-2025-9820.json">CVE-2025-9820</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:82347
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:82354
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:82372

      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)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2025/9xxx/CVE-2025-9820.json">CVE-2025-9820</a>

      Source identifier: secalert@redhat.com

    4. Record modifiedSiemens ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-032379.html
      Referenceremoved
      https://cert-portal.siemens.com/productcert/html/ssa-032379.html
      —

      Source identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

    5. Record modifiedRed Hat

      Show 29 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/2025/9xxx/CVE-2025-9820.json">CVE-2025-9820</a>
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:13812
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:3477
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:4188
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:4655
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:4943
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:5585
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:5606
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:7329
      Referenceadded
      —
      https://access.redhat.com/errata/RHSA-2026:7477
      Referenceadded
      —
      https://access.redhat.com/security/cve/CVE-2025-9820
      Referenceadded
      —
      https://bugzilla.redhat.com/show_bug.cgi?id=2392528
      Referenceadded
      —
      https://gitlab.com/gnutls/gnutls/-/commit/1d56f96f6ab5034d677136b9d50b5a75dff0faf5
      Referenceadded
      —
      https://gitlab.com/gnutls/gnutls/-/issues/1732
      Referenceadded
      —
      https://www.gnutls.org/security-new.html#GNUTLS-SA-2025-11-18
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:13812
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:3477
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:4188
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:4655
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:4943
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:5585
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:5606
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7329
      —
      Referenceremoved
      https://access.redhat.com/errata/RHSA-2026:7477
      —
      Referenceremoved
      https://access.redhat.com/security/cve/CVE-2025-9820
      —
      Referenceremoved
      https://bugzilla.redhat.com/show_bug.cgi?id=2392528
      —
      Referenceremoved
      https://gitlab.com/gnutls/gnutls/-/commit/1d56f96f6ab5034d677136b9d50b5a75dff0faf5
      —
      Referenceremoved
      https://gitlab.com/gnutls/gnutls/-/issues/1732
      —
      Referenceremoved
      https://www.gnutls.org/security-new.html#GNUTLS-SA-2025-11-18
      —

      Source identifier: secalert@redhat.com

    Show 2 older changes

    1. Record modifiedCVE Program

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      http://www.openwall.com/lists/oss-security/2025/11/20/2
      Referenceremoved
      http://www.openwall.com/lists/oss-security/2025/11/20/2
      —

      Source identifier: af854a3a-2127-422b-91ae-364da2661108

    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
      Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 8 (+21)
      Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 8 (+21)

      Source identifier: secalert@redhat.com

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