HighCVE-2026-89603

    Linux Kernel: Race Condition (CVE-2026-89603)

    Published Last modified Sources: SUSE, HKCERT, Debian, Red Hat, BSI, CVE.org

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    What is affected, what to do

    A flaw was found in the Linux kernel. A race condition exists where a seccomp filter, intended to restrict system calls, can be bypassed by an unprivileged process.

    Update Linux Kernel to version 5.10.270, Linux Kernel to version 5.15.221, Linux Kernel to version 6.1.188.

    Affected
    • Linux Kernel lt 5.9..5.10.270
    • Linux Kernel lt 5.11..5.15.221
    • Linux Kernel lt 5.16..6.1.188
    • Linux Kernel lt 6.2..6.6.157
    • Linux Kernel lt 6.7..6.12.110
    • Linux Kernel lt 6.13..6.18.51
    • Linux Kernel lt 6.19..7.2.4
    • Linux Kernel lt 7.3..7.3-rc1
    Fixed in
    • Linux Kernel 5.10.270
    • Linux Kernel 5.15.221
    • Linux Kernel 6.1.188
    • Linux Kernel 6.6.157
    • Linux Kernel 6.12.110
    • Linux Kernel 6.18.51
    • Linux Kernel 7.2.4
    • Linux Kernel 7.3-rc1

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

    Metrics

    8.4

    Priority

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

    Source: Vendor (CNA), CVSS v3

    8.4

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: SUSE, HKCERT, Debian, Red Hat, BSI, CVE.org

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 3.2

    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
    67.53 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
    8.4 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
    8.4
    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
    0.1 %
    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
    3.2
    Low — this CVE sits in the lower 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

    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 the Linux kernel. A race condition exists where a seccomp filter, intended to restrict system calls, can be bypassed by an unprivileged process. This occurs when a thread is stopped for tracing (ptrace) and another thread attempts to apply a seccomp filter with the `SECCOMP_FILTER_FLAG_TSYNC` flag. Due to a caching issue, the newly installed filter is not properly enforced, allowing the unprivileged process to execute system calls that should have been blocked, potentially leading to a security bypass.

    Source: suse_csaf, HKCERT (CC BY 3.0 HK) · HKCERT rating: medium, Debian Security Advisories, redhat_csaf, BSI WID Portal, BSI CSAF, NVD (NIST), cvelistv5

    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
    • 5.9 – < 5.10.270
    • 6.13 – < 6.18.51
    • 7.3 – < 7.3-rc1
    • 5.11 – < 5.15.221
    • 6.7 – < 6.12.110
    • 5.16 – < 6.1.188
    • 6.2 – < 6.6.157
    • 6.19 – < 7.2.4
    • 5.10.270
    • 6.18.51
    • 7.3-rc1
    • 5.15.221
    • 6.12.110
    • 6.1.188
    • 6.6.157
    • 7.2.4

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxtrixie

    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. RejectedLinux

    2. Record modifiedLinux

      CVSS V3.1: before kernel.org: AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N, after —

      Description added or changed

      Show 11 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionchanged
      In the Linux kernel, the following vulnerability has been resolved: entry: Fix seccomp bypass after ptrace with TSYNC Sashiko review pointed out the following issue. If a thread is stopped in syscall_trace_enter() for ptrace, another thread can install a seccomp filter with SECCOMP_FILTER_FLAG_TSYNC (e.g., via seccomp_attach_filter()). This will successfully set SYSCALL_WORK_SECCOMP on the stopped thread, but syscall_trace_enter() evaluates a cached 'work' variable sampled on entry. Consequently, the subsequent check for SYSCALL_WORK_SECCOMP misses the newly assigned flag, and the filter is silently bypassed. This race condition could allow an unprivileged process to execute a prohibited system call (e.g., execve) that the newly installed filter was intended to block, especially since the tracer might have modified the system call number during the ptrace stop. Fix this by re-reading the syscall_work flags after ptrace handling, so that any new SYSCALL_WORK_SECCOMP flag set by another thread via TSYNC during the ptrace stop is observed before the subsequent seccomp check.
      Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.
      CVSSremoved
      kernel.org: AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
      —
      Affected versions (publisher)added
      —
      Affected value removed. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/89xxx/CVE-2026-89603.json">CVE-2026-89603</a>
      Referenceremoved
      kernel.org: https://git.kernel.org/stable/c/09e8880ce5409bdb84da991b053d7087502c181e
      —
      Referenceremoved
      kernel.org: https://git.kernel.org/stable/c/22bb836fc133331982c264227a899d4b26a09706
      —
      Referenceremoved
      kernel.org: https://git.kernel.org/stable/c/23001ee5d8631e30192cde6f6d3ccb6805570499
      —
      Referenceremoved
      kernel.org: https://git.kernel.org/stable/c/459f33f82864723a7fa366cf1091d9c6c893b6b2
      —
      Referenceremoved
      kernel.org: https://git.kernel.org/stable/c/4a3591287fb7f808e209b4974ed337f609a2006b
      —
      Referenceremoved
      kernel.org: https://git.kernel.org/stable/c/8709e7e1dd7d7de0651e61700edf24f5784f9243
      —
      Referenceremoved
      kernel.org: https://git.kernel.org/stable/c/ab4647459098a43e9d6fdb860836f08c962f3774
      —
      Referenceremoved
      kernel.org: https://git.kernel.org/stable/c/eca5ed4200f0be3e91f8a237b1f37582030a93a8
      —

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

    3. Record modifiedLinux

      Show 6 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-2026-89603.json">CVE-2026-89603</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/09e8880ce5409bdb84da991b053d7087502c181e
      Referenceadded
      —
      https://git.kernel.org/stable/c/22bb836fc133331982c264227a899d4b26a09706
      Referenceadded
      —
      https://git.kernel.org/stable/c/23001ee5d8631e30192cde6f6d3ccb6805570499
      Referenceadded
      —
      https://git.kernel.org/stable/c/8709e7e1dd7d7de0651e61700edf24f5784f9243
      Referenceadded
      —
      https://git.kernel.org/stable/c/eca5ed4200f0be3e91f8a237b1f37582030a93a8

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

    4. Record modifiedLinux

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

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

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

    5. ReceivedLinux

      Description added or changed

      Show 5 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: entry: Fix seccomp bypass after ptrace with TSYNC Sashiko review pointed out the following issue. If a thread is stopped in syscall_trace_enter() for ptrace, another thread can install a seccomp filter with SECCOMP_FILTER_FLAG_TSYNC (e.g., via seccomp_attach_filter()). This will successfully set SYSCALL_WORK_SECCOMP on the stopped thread, but syscall_trace_enter() evaluates a cached 'work' variable sampled on entry. Consequently, the subsequent check for SYSCALL_WORK_SECCOMP misses the newly assigned flag, and the filter is silently bypassed. This race condition could allow an unprivileged process to execute a prohibited system call (e.g., execve) that the newly installed filter was intended to block, especially since the tracer might have modified the system call number during the ptrace stop. Fix this by re-reading the syscall_work flags after ptrace handling, so that any new SYSCALL_WORK_SECCOMP flag set by another thread via TSYNC during the ptrace stop is observed before the subsequent seccomp check.
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/89xxx/CVE-2026-89603.json">CVE-2026-89603</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/459f33f82864723a7fa366cf1091d9c6c893b6b2
      Referenceadded
      —
      https://git.kernel.org/stable/c/4a3591287fb7f808e209b4974ed337f609a2006b
      Referenceadded
      —
      https://git.kernel.org/stable/c/ab4647459098a43e9d6fdb860836f08c962f3774

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

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