MediumCVE-2026-80844

    Linux Kernel: Out-of-Bounds Access (CVE-2026-80844)

    Published Last modified Sources: SUSE, Red Hat, HKCERT, Ubuntu, Debian LTS, Debian, CVE.org, EUVD, Msrc Update Guide, BSI

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    What is affected, what to do

    A flaw was found in the Linux kernel's xfrm subsystem, specifically within the AH6 (Authentication Header for IPv6) module. The `ipv6_rearrange_rthdr()` function does not properly validate the `segments_left` field in routing headers when processing raw IPv6 HDRINCL packets.

    An exploit is publicly available. Update Linux Kernel to version 5.10.269, Linux Kernel to version 5.15.220, Linux Kernel to version 6.1.187.

    Affected
    • Linux Kernel lt 2.6.12..5.10.269
    • Linux Kernel lt 5.11..5.15.220
    • Linux Kernel lt 5.16..6.1.187
    • Linux Kernel lt 6.2..6.6.156
    • Linux Kernel lt 6.7..6.12.108
    • Linux Kernel lt 6.13..6.18.49
    • Linux Kernel lt 6.19..7.1.13
    • Linux Kernel lt 7.2..7.2.3
    Fixed in
    • Linux Kernel 5.10.269
    • Linux Kernel 5.15.220
    • Linux Kernel 6.1.187
    • Linux Kernel 6.6.156
    • Linux Kernel 6.12.108
    • Linux Kernel 6.18.49
    • Linux Kernel 7.1.13
    • Linux Kernel 7.2.3
    • Linux Kernel 7.3

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

    Metrics

    6.0

    XIEM Effective CVSS

    Highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    6.0

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: SUSE, Red Hat, HKCERT, Ubuntu, Debian LTS, Debian, CVE.org, EUVD, Msrc Update Guide, BSI

    0.4 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 38.1

    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
    65.60 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
    PoC (publicly reported)
    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
    6.0 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
    6.0
    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
    0.4 %
    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
    38.1
    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
    CISA assessment (SSVC)
    Exploitation: none known · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 6 November 2026

    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 Linux kernel's xfrm subsystem, specifically within the AH6 (Authentication Header for IPv6) module. The `ipv6_rearrange_rthdr()` function does not properly validate the `segments_left` field in routing headers when processing raw IPv6 HDRINCL packets. This oversight allows an attacker to craft a malicious packet that can cause an out-of-bounds memory access, potentially leading to memory corruption.

    Source: suse_csaf, redhat_csaf, HKCERT (CC BY 3.0 HK) · HKCERT rating: medium, Ubuntu Security Notices, Debian LTS Advisories, Debian Security Advisories, cvelistv5, NVD (NIST), CVE.org (MITRE), ENISA EUVD, Microsoft Security Update Guide, 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
    • 6.13 – < 6.18.49
    • 5.11 – < 5.15.220
    • 2.6.12 – < 5.10.269
    • 5.16 – < 6.1.187
    • 6.7 – < 6.12.108
    • 7.2 – < 7.2.3
    • —
    • 6.19 – < 7.1.13
    • 6.2 – < 6.6.156
    • 6.18.49
    • 5.15.220
    • 5.10.269
    • 6.1.187
    • 6.12.108
    • 7.2.3
    • 7.3
    • 7.1.13
    • 6.6.156
    Red HatOpenShift
    • Container Platform
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinuxtrixie
    Linuxubuntulinuxjammy
    Linuxubuntulinuxnoble
    Linuxubuntulinuxresolute
    Linuxdebianlinux-6.12bookworm
    Linuxubuntulinux-awsjammy
    Linuxubuntulinux-awsnoble
    Linuxubuntulinux-awsresolute
    Linuxubuntulinux-aws-5.15focal
    Linuxubuntulinux-aws-6.8jammy
    Linuxubuntulinux-aws-7.0noble
    Linuxubuntulinux-aws-fipsjammy
    Linuxubuntulinux-aws-fipsnoble
    Linuxubuntulinux-azurejammy
    Linuxubuntulinux-azurenoble
    Linuxubuntulinux-azureresolute
    Linuxubuntulinux-azure-5.15focal
    Linuxubuntulinux-azure-6.8jammy
    Linuxubuntulinux-azure-fdejammy
    Linuxubuntulinux-azure-fdenoble
    Linuxubuntulinux-azure-fderesolute
    Linuxubuntulinux-azure-fde-5.15focal
    Linuxubuntulinux-azure-fde-6.8jammy

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    PoC-in-GitHub (nomi-sec)dirtyah6 (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2026-80844 (opens in a new tab)github.comPoC (publicly reported)reported, not verified
    PoC-in-GitHub (nomi-sec)CVE-2026-80844 (opens in a new tab)github.comPoC (publicly reported)reported, not verified

    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 modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-80844","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-11-06T17:03:43.679376Z"}

      Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

    2. 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/2026/80xxx/CVE-2026-80844.json">CVE-2026-80844</a>

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

    3. ReceivedLinux

      Description added or changed

      Show 11 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: xfrm: ah6: validate routing header segments_left AH6 rearranges routing-header addresses before computing or verifying the ICV. ipv6_rearrange_rthdr() assumes that segments_left is not larger than the number of addresses described by the routing header's hdrlen field. That assumption does not hold for raw IPv6 HDRINCL packets. A packet with hdrlen equal to 2 describes one address, but can carry an arbitrary segments_left value. With segments_left equal to 255, the function moves its address pointer 4,064 bytes backwards and passes a 4,064-byte length to memmove(), resulting in an out-of-bounds access. Validate the invariant locally before modifying the routing header or performing any address-pointer arithmetic, and propagate malformed-header errors to the existing AH6 input and output error paths.
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/80xxx/CVE-2026-80844.json">CVE-2026-80844</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/0bf11081ad3753938a2b48723ce6298dbac743a1
      Referenceadded
      —
      https://git.kernel.org/stable/c/1516e31ac458a738be485620579d8f7fb2700fcb
      Referenceadded
      —
      https://git.kernel.org/stable/c/1b7e066eabcc7d6d8f476c34739b45932f2f4c31
      Referenceadded
      —
      https://git.kernel.org/stable/c/2dc650956e4e163b879b3fb1027f9557abc5c985
      Referenceadded
      —
      https://git.kernel.org/stable/c/46640c814f25f096b0b0045ca50e1b7030cd8a30
      Referenceadded
      —
      https://git.kernel.org/stable/c/48b0e36cf54358276ee7aa897034c973097d2bc9
      Referenceadded
      —
      https://git.kernel.org/stable/c/6733ae71268a27d598cfb3f3339a3c950b9b656d
      Referenceadded
      —
      https://git.kernel.org/stable/c/7bad4bda74dc4713f398d3b7624ff05478e3a568
      Referenceadded
      —
      https://git.kernel.org/stable/c/f00df8500e5a36ba70d336fd34bd2152ea074e5f

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

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