CriticalCVE-2026-89702

    Linux Kernel: security vulnerability (CVE-2026-89702)

    Published Last modified Sources: HKCERT, Ubuntu, SUSE, Debian LTS, Debian, CVE.org, EUVD, BSI

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    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: nfsd: size fh_verify server sockaddr slot by xpt_locallen The nfsd_fh_verify and nfsd_fh_verify_err tracepoints declare the server sockaddr slot sized by xpt_remotelen but fill it from xpt_local using xpt_locallen: TP_STRUCT__entry( ... __sockaddr(server, rqstp->rq_xprt->xpt_remotelen) ... ) TP_fast_assign( ... __assign_sockaddr(server, &rqstp->rq_xprt->xpt_local, rqstp->rq_xprt->xpt_locallen); ... ) When xpt_locallen exceeds xpt_remotelen, __assign_sockaddr's memcpy writes past the reserved ring-buffer slot. In the reverse direction (xpt_locallen < xpt_remotelen) the slot is oversized and the unwritten tail leaks prior ring-buffer contents to trace consumers.

    Update Linux Kernel to version 5.15.224, Linux Kernel to version 6.1.191, Linux Kernel to version 6.6.160.

    Affected
    • Linux Kernel lt 5.15.154..5.15.224
    • Linux Kernel lt 6.0..6.1.191
    • Linux Kernel lt 6.2..6.6.160
    • Linux Kernel lt 6.7..6.12.109
    • Linux Kernel lt 6.13..6.18.50
    • Linux Kernel lt 6.19..7.2.4
    Fixed in
    • Linux Kernel 5.15.224
    • Linux Kernel 6.1.191
    • Linux Kernel 6.6.160
    • Linux Kernel 6.12.109
    • Linux Kernel 6.18.50
    • Linux Kernel 7.2.4
    • Linux Kernel 7.3

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

    Metrics

    9.8

    XIEM Effective CVSS

    Highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: HKCERT, Ubuntu, SUSE, Debian LTS, Debian, CVE.org, EUVD, BSI

    0.5 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 43.5

    Show all metrics
    Severity
    Critical
    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
    88.91 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
    9.8 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
    9.8
    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
    43.5
    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

    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

    In the Linux kernel, the following vulnerability has been resolved: nfsd: size fh_verify server sockaddr slot by xpt_locallen The nfsd_fh_verify and nfsd_fh_verify_err tracepoints declare the server sockaddr slot sized by xpt_remotelen but fill it from xpt_local using xpt_locallen: TP_STRUCT__entry( ... __sockaddr(server, rqstp->rq_xprt->xpt_remotelen) ... ) TP_fast_assign( ... __assign_sockaddr(server, &rqstp->rq_xprt->xpt_local, rqstp->rq_xprt->xpt_locallen); ... ) When xpt_locallen exceeds xpt_remotelen, __assign_sockaddr's memcpy writes past the reserved ring-buffer slot. In the reverse direction (xpt_locallen < xpt_remotelen) the slot is oversized and the unwritten tail leaks prior ring-buffer contents to trace consumers. The write-past-end case is reachable on NFS/UDP. svc_xprt_set_remote() is only called from svc_tcp_accept() (net/sunrpc/svcsock.c) and from the RDMA connect path; svc_create_socket() for UDP calls only svc_xprt_set_local(), so xpt_remotelen stays 0 for the xprt's lifetime. Every fh_verify trace for an NFSv2/v3-over-UDP request then copies 16 or 28 bytes from xpt_local into a zero-byte slot. The other NFSD tracepoints that record the server address (NFSD_TRACE_PROC_CALL_FIELDS, NFSD_TRACE_PROC_RES_FIELDS, SVC_RQST_ENDPOINT_FIELDS) already size the server slot by xpt_locallen; nfsd_fh_verify and nfsd_fh_verify_err were the only exceptions. Fix by sizing the server slot with xpt_locallen so the declared slot matches the copy length. The client slot and its assignment already agree on xpt_remotelen and are left untouched.

    Source: HKCERT (CC BY 3.0 HK) · HKCERT rating: medium, Ubuntu Security Notices, suse_csaf, Debian LTS Advisories, Debian Security Advisories, cvelistv5, NVD (NIST), ENISA EUVD, 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
    LinuxLinux
    • 5.15.154 – < 5.15.224
    • —
    • 6.2 – < 6.6.160
    • 6.13 – < 6.18.50
    • 6.19 – < 7.2.4
    • 6.7 – < 6.12.109
    • 6.0 – < 6.1.191
    • 5.15.224
    • 7.3
    • 6.6.160
    • 6.18.50
    • 7.2.4
    • 6.12.109
    • 6.1.191
    Red HatOpenShift
    • Container Platform
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxtrixie
    Linuxubuntulinuxnoble
    Linuxubuntulinuxresolute
    Linuxdebianlinux-6.12bookworm
    Linuxubuntulinux-awsnoble
    Linuxubuntulinux-awsresolute
    Linuxubuntulinux-aws-6.8jammy
    Linuxubuntulinux-aws-7.0noble
    Linuxubuntulinux-aws-fipsnoble
    Linuxubuntulinux-azurenoble
    Linuxubuntulinux-azureresolute
    Linuxubuntulinux-azure-6.8jammy
    Linuxubuntulinux-azure-fdenoble
    Linuxubuntulinux-azure-fderesolute
    Linuxubuntulinux-azure-fde-6.8jammy
    Linuxubuntulinux-azure-fde-7.0noble
    Linuxubuntulinux-azure-fipsnoble
    Linuxubuntulinux-gcpnoble
    Linuxubuntulinux-gcpresolute
    Linuxubuntulinux-gcp-6.8jammy
    Linuxubuntulinux-gcp-7.0noble
    Linuxubuntulinux-gcp-fipsnoble
    Linuxubuntulinux-gkenoble
    Linuxubuntulinux-gkeresolute

    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 modifiedLinux

      Show 3 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/2026/89xxx/CVE-2026-89702.json">CVE-2026-89702</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/4c7569ad68fc8b86ca40c7e56ef21460c0344955
      Referenceadded
      —
      https://git.kernel.org/stable/c/50d9d581d2af80799125ee62617d37e9b6b476a7

      Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    2. Record modifiedLinux

      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/2026/89xxx/CVE-2026-89702.json">CVE-2026-89702</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/1c6a4d6c20fd42552ffc2c3dfaed2139c9477ee5

      Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    3. Record modifiedLinux

      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/2026/89xxx/CVE-2026-89702.json">CVE-2026-89702</a>

      Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    4. Record modifiedLinux

      CVSS V3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      CVSSadded
      —
      AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

      Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

    5. ReceivedLinux

      Description added or changed

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: nfsd: size fh_verify server sockaddr slot by xpt_locallen The nfsd_fh_verify and nfsd_fh_verify_err tracepoints declare the server sockaddr slot sized by xpt_remotelen but fill it from xpt_local using xpt_locallen: TP_STRUCT__entry( ... __sockaddr(server, rqstp->rq_xprt->xpt_remotelen) ... ) TP_fast_assign( ... __assign_sockaddr(server, &rqstp->rq_xprt->xpt_local, rqstp->rq_xprt->xpt_locallen); ... ) When xpt_locallen exceeds xpt_remotelen, __assign_sockaddr's memcpy writes past the reserved ring-buffer slot. In the reverse direction (xpt_locallen < xpt_remotelen) the slot is oversized and the unwritten tail leaks prior ring-buffer contents to trace consumers. The write-past-end case is reachable on NFS/UDP. svc_xprt_set_remote() is only called from svc_tcp_accept() (net/sunrpc/svcsock.c) and from the RDMA connect path; svc_create_socket() for UDP calls only svc_xprt_set_local(), so xpt_remotelen stays 0 for the xprt's lifetime. Every fh_verify trace for an NFSv2/v3-over-UDP request then copies 16 or 28 bytes from xpt_local into a zero-byte slot. The other NFSD tracepoints that record the server address (NFSD_TRACE_PROC_CALL_FIELDS, NFSD_TRACE_PROC_RES_FIELDS, SVC_RQST_ENDPOINT_FIELDS) already size the server slot by xpt_locallen; nfsd_fh_verify and nfsd_fh_verify_err were the only exceptions. Fix by sizing the server slot with xpt_locallen so the declared slot matches the copy length. The client slot and its assignment already agree on xpt_remotelen and are left untouched.
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/89xxx/CVE-2026-89702.json">CVE-2026-89702</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/719a10e3f5f868c3c4ac3cf3648c5775d12034bd
      Referenceadded
      —
      https://git.kernel.org/stable/c/71d068490098b1d23c63b2345e40675d3a1ca763
      Referenceadded
      —
      https://git.kernel.org/stable/c/7ff8d6363cffff45654ea85e319f7c0c54226012
      Referenceadded
      —
      https://git.kernel.org/stable/c/95d064f9828a20ccca5ae90a17be3e2076f25272

      Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

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