HighCVE-2026-46193

    Linux Kernel: security vulnerability (CVE-2026-46193)

    Published Last modified Sources: SUSE, Siemens ProductCERT, Debian LTS, Ubuntu, BSI, CVE.org, Msrc Update Guide, EUVD

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    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: xfrm: ah: account for ESN high bits in async callbacks AH allocates its temporary auth/ICV layout differently when ESN is enabled: the async ahash setup appends a 4-byte seqhi slot before the ICV or auth_data area, but the async completion callbacks still reconstruct the temporary layout as if seqhi were absent. With an async AH implementation selected, that makes AH copy or compare the wrong bytes on both the IPv4 and IPv6 paths.

    Update Linux Kernel to version 5.15.210, Linux Kernel to version 6.1.176, Linux Kernel to version 6.6.140.

    Affected
    • Linux Kernel lt 3.15..5.15.210
    • Linux Kernel lt 5.16..6.1.176
    • Linux Kernel lt 6.2..6.6.140
    • Linux Kernel lt 6.7..6.12.88
    • Linux Kernel lt 6.13..6.18.30
    • Linux Kernel lt 6.19..7.0.7
    Fixed in
    • Linux Kernel 5.15.210
    • Linux Kernel 6.1.176
    • Linux Kernel 6.6.140
    • Linux Kernel 6.12.88
    • Linux Kernel 6.18.30
    • Linux Kernel 7.0.7
    • Linux Kernel 7.1

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

    Metrics

    7.1

    Priority

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

    Source: Vendor (CNA), CVSS v3

    5.5

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: SUSE, Siemens ProductCERT, Debian LTS, Ubuntu, BSI, CVE.org, Msrc Update Guide, EUVD

    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
    45.30 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
    7.1 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
    5.5
    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

    In the Linux kernel, the following vulnerability has been resolved: xfrm: ah: account for ESN high bits in async callbacks AH allocates its temporary auth/ICV layout differently when ESN is enabled: the async ahash setup appends a 4-byte seqhi slot before the ICV or auth_data area, but the async completion callbacks still reconstruct the temporary layout as if seqhi were absent. With an async AH implementation selected, that makes AH copy or compare the wrong bytes on both the IPv4 and IPv6 paths. In UML repro on IPv4 AH with ESN and forced async hmac(sha1), ping fails with 100% packet loss, and the callback logs show the pre-fix drift: ah4 output_done: esn=1 err=0 icv_off=20 expected_off=24 ah4 input_done: esn=1 auth_off=20 expected_auth_off=24 icv_off=32 expected_icv_off=36 Reconstruct the callback-side layout the same way the setup path built it by skipping the ESN seqhi slot before locating the saved auth_data or ICV. Per RFC 4302, the ESN high-order 32 bits participate in the AH ICV computation, so the async callbacks must account for the seqhi slot. Post-fix, the same IPv4 AH+ESN+forced-async-hmac(sha1) UML repro shows the corrected offset (ah4 output_done: esn=1 err=0 icv_off=24 expected_off=24) and ping succeeds; net/ipv4/ah4.o and net/ipv6/ah6.o build clean at W=1. IPv6 AH+ESN was not exercised at runtime, and the change has not been tested against a real async hardware AH engine.

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

    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
    • 6.7 – < 6.12.88
    • 6.2 – < 6.6.140
    • 6.19 – < 7.0.7
    • —
    • 3.15 – < 5.15.210
    • 5.16 – < 6.1.176
    • 6.13 – < 6.18.30
    • 6.12.88
    • 6.6.140
    • 7.0.7
    • 7.1
    • 5.15.210
    • 6.1.176
    • 6.18.30
    SiemensSIMATIC S7
    • 1500 TM MFP V1.1.1 GNU/Linux subsystem
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinux-6.1bullseye
    Linuxubuntulinux-nvidiajammy
    Linuxubuntulinux-nvidia-tegrajammy
    Linuxubuntulinux-nvidia-tegra-5.15focal
    Linuxubuntulinux-nvidia-tegra-igxjammy
    Linuxlinuxlinux_kernel7.1
    Linuxlinuxlinux_kernel—

    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 modifiedSiemens ADP

      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/2026/46xxx/CVE-2026-46193.json">CVE-2026-46193</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-457936.html
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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

    2. Record modifiedLinux

      Show 19 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/0555d4f526232b3c9e3afbcd490c0c0793aefec6
      Referenceadded
      —
      https://git.kernel.org/stable/c/1dae77078ceb4bab833f7a4935f05c5b8c97b9ba
      Referenceadded
      —
      https://git.kernel.org/stable/c/2ffaa7a94f9a4d22724364a1821735a0231d9f8d
      Referenceadded
      —
      https://git.kernel.org/stable/c/729899a2aa8bda7844be0cdcd3b470f11b912eda
      Referenceadded
      —
      https://git.kernel.org/stable/c/7db99a09b3bc87268287bc7ab5f2e7f382b5ad87
      Referenceadded
      —
      https://git.kernel.org/stable/c/ec406c26c97594124e79d14516b729a8d5dced62
      Referenceadded
      —
      https://git.kernel.org/stable/c/ec54093e6a8f87e800bb6aa15eb7fc1e33faa524
      Referenceremoved
      https://git.kernel.org/stable/c/0555d4f526232b3c9e3afbcd490c0c0793aefec6
      —
      Referenceremoved
      https://git.kernel.org/stable/c/1dae77078ceb4bab833f7a4935f05c5b8c97b9ba
      —
      Referenceremoved
      https://git.kernel.org/stable/c/2ffaa7a94f9a4d22724364a1821735a0231d9f8d
      —
      Referenceremoved
      https://git.kernel.org/stable/c/729899a2aa8bda7844be0cdcd3b470f11b912eda
      —
      Referenceremoved
      https://git.kernel.org/stable/c/7db99a09b3bc87268287bc7ab5f2e7f382b5ad87
      —
      Referenceremoved
      https://git.kernel.org/stable/c/ec406c26c97594124e79d14516b729a8d5dced62
      —
      Referenceremoved
      https://git.kernel.org/stable/c/ec54093e6a8f87e800bb6aa15eb7fc1e33faa524
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/0555d4f526232b3c9e3afbcd490c0c0793aefec6 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/2ffaa7a94f9a4d22724364a1821735a0231d9f8d Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/729899a2aa8bda7844be0cdcd3b470f11b912eda Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/7db99a09b3bc87268287bc7ab5f2e7f382b5ad87 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/ec54093e6a8f87e800bb6aa15eb7fc1e33faa524 Types: Patch
      —

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

    3. Record modifiedSiemens ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/46xxx/CVE-2026-46193.json">CVE-2026-46193</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-019113.html

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

    4. Record modifiedLinux

      Show 3 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/1dae77078ceb4bab833f7a4935f05c5b8c97b9ba
      Referenceadded
      —
      https://git.kernel.org/stable/c/ec406c26c97594124e79d14516b729a8d5dced62
      Affected versions (publisher)changed
      Linux, Linux
      Linux, Linux

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

    5. Initial analysis by NVDNVD

      Newly listed as affected:
      • Linux Kernel (6.13 – before 6.18.30; 6.19 – before 7.0.7; 6.7 – before 6.12.88; 3.15 – before 6.6.140; 2 individual versions)

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

      Show 8 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      CVSSadded
      —
      AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
      Weakness type (CWE)added
      —
      NVD-CWE-noinfo
      Product configurationadded
      —
      OR *cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.18.30 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 7.0.7 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.88 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 3.15 up to (excluding) 6.6.140
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/0555d4f526232b3c9e3afbcd490c0c0793aefec6 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/2ffaa7a94f9a4d22724364a1821735a0231d9f8d Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/729899a2aa8bda7844be0cdcd3b470f11b912eda Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/7db99a09b3bc87268287bc7ab5f2e7f382b5ad87 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/ec54093e6a8f87e800bb6aa15eb7fc1e33faa524 Types: Patch

      Source identifier: nvd@nist.gov

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