HighCVE-2025-21719

    Linux Kernel: security vulnerability (CVE-2025-21719)

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

    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: ipmr: do not call mr_mfc_uses_dev() for unres entries syzbot found that calling mr_mfc_uses_dev() for unres entries would crash [1], because c->mfc_un.res.minvif / c->mfc_un.res.maxvif alias to "struct sk_buff_head unresolved", which contain two pointers. This code never worked, lets remove it. [1] Unable to handle kernel paging request at virtual address ffff5fff2d536613 KASAN: maybe wild-memory-access in range [0xfffefff96a9b3098-0xfffefff96a9b309f] Modules linked in: CPU: 1 UID: 0 PID: 7321 Comm: syz.0.16 Not tainted 6.13.0-rc7-syzkaller-g1950a0af2d55 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : mr_mfc_uses_dev net/ipv4/ipmr_base.c:290 [inline] pc : mr_table_dump+0x5a4/0x8b0 net/ipv4/ipmr_base.c:334 lr : mr_mfc_uses_dev net/ipv4/ipmr_base.c:289 [inline] lr : mr_table_dump+0x694/0x8b0 net/ipv4/ipmr_base.c:334 Call trace: mr_mfc_uses_dev net/ipv4/ipmr_base.c:290 [inline] (P) mr_table_dump+0x5a4/0x8b0 net/ipv4/ipmr_base.c:334 (P) mr_rtm_dumproute+0x254/0x454 net/ipv4/ipmr_base.c:382 ipmr_rtm_dumproute+0x248/0x4b4 net/ipv4/ipmr.c:2648 rtnl_dump_all+0x2e4/0x4e8 net/core/rtnetlink.c:4327 rtnl_dumpit+0x98/0x1d0 net/core/rtnetlink.c:6791 netlink_dump+0x4f0/0xbc0 net/netlink/af_netlink.c:2317 netlink_recvmsg+0x56c/0xe64 net/netlink/af_netlink.c:1973 sock_recvmsg_nosec net/socket.c:1033 [inline] sock_recvmsg net/socket.c:1055 [inline] sock_read_iter+0x2d8/0x40c net/socket.c:1125 new_sync_read fs/read_write.c:484 [inline] vfs_read+0x740/0x970 fs/read_write.c:565 ksys_read+0x15c/0x26c fs/read_write.c:708

    Update Linux Kernel to version 5.4.291, Linux Kernel to version 5.10.235, Linux Kernel to version 5.15.179.

    Affected
    • Linux Kernel lt 4.20..5.4.291
    • Linux Kernel lt 5.5..5.10.235
    • Linux Kernel lt 5.11..5.15.179
    • Linux Kernel lt 5.16..6.1.129
    • Linux Kernel lt 6.2..6.6.76
    • Linux Kernel lt 6.7..6.12.13
    • Linux Kernel lt 6.13..6.13.2
    Fixed in
    • Linux Kernel 5.4.291
    • Linux Kernel 5.10.235
    • Linux Kernel 5.15.179
    • Linux Kernel 6.1.129
    • Linux Kernel 6.6.76
    • Linux Kernel 6.12.13
    • Linux Kernel 6.13.2
    • Linux Kernel 6.14

    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: NVD, CVSS v3

    7.1

    CVSS v3

    Severity High on the scale from 0 to 10.

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

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 10.7

    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
    44.41 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
    7.1
    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
    10.7
    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
    CISA assessment (SSVC)
    Exploitation: none known · not automatable · Technical impact: partial
    Source: CISA Vulnrichment, as of 15 October 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
    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: ipmr: do not call mr_mfc_uses_dev() for unres entries syzbot found that calling mr_mfc_uses_dev() for unres entries would crash [1], because c->mfc_un.res.minvif / c->mfc_un.res.maxvif alias to "struct sk_buff_head unresolved", which contain two pointers. This code never worked, lets remove it. [1] Unable to handle kernel paging request at virtual address ffff5fff2d536613 KASAN: maybe wild-memory-access in range [0xfffefff96a9b3098-0xfffefff96a9b309f] Modules linked in: CPU: 1 UID: 0 PID: 7321 Comm: syz.0.16 Not tainted 6.13.0-rc7-syzkaller-g1950a0af2d55 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : mr_mfc_uses_dev net/ipv4/ipmr_base.c:290 [inline] pc : mr_table_dump+0x5a4/0x8b0 net/ipv4/ipmr_base.c:334 lr : mr_mfc_uses_dev net/ipv4/ipmr_base.c:289 [inline] lr : mr_table_dump+0x694/0x8b0 net/ipv4/ipmr_base.c:334 Call trace: mr_mfc_uses_dev net/ipv4/ipmr_base.c:290 [inline] (P) mr_table_dump+0x5a4/0x8b0 net/ipv4/ipmr_base.c:334 (P) mr_rtm_dumproute+0x254/0x454 net/ipv4/ipmr_base.c:382 ipmr_rtm_dumproute+0x248/0x4b4 net/ipv4/ipmr.c:2648 rtnl_dump_all+0x2e4/0x4e8 net/core/rtnetlink.c:4327 rtnl_dumpit+0x98/0x1d0 net/core/rtnetlink.c:6791 netlink_dump+0x4f0/0xbc0 net/netlink/af_netlink.c:2317 netlink_recvmsg+0x56c/0xe64 net/netlink/af_netlink.c:1973 sock_recvmsg_nosec net/socket.c:1033 [inline] sock_recvmsg net/socket.c:1055 [inline] sock_read_iter+0x2d8/0x40c net/socket.c:1125 new_sync_read fs/read_write.c:484 [inline] vfs_read+0x740/0x970 fs/read_write.c:565 ksys_read+0x15c/0x26c fs/read_write.c:708

    Source: siemens_advisory, BSI CSAF, BSI WID Portal, 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
    LinuxLinux
    • 5.5 – < 5.10.235
    • 6.13 – < 6.13.2
    • —
    • 5.16 – < 6.1.129
    • 5.11 – < 5.15.179
    • 4.20 – < 5.4.291
    • 6.7 – < 6.12.13
    • 6.2 – < 6.6.76
    • 5.10.235
    • 6.13.2
    • 6.14
    • 6.1.129
    • 5.15.179
    • 5.4.291
    • 6.12.13
    • 6.6.76
    DellSecure Connect Gateway
    • < 5.30.0.14
    • 5.30.0.14
    SiemensSIMATIC S7
    • 1500 TM MFP V1.1.1 GNU/Linux subsystem
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbullseye
    Linuxdebianlinux-6.1bullseye
    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 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-2025-21719","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-10-15T21:42:48.262327Z"}

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

    2. Record modifiedLinux

      Show 24 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/15a901361ec3fb1c393f91880e1cbf24ec0a88bd
      Referenceadded
      —
      https://git.kernel.org/stable/c/26bb7d991f04eeef47dfad23e533834995c26f7a
      Referenceadded
      —
      https://git.kernel.org/stable/c/53df27fd38f84bd3cd6b004eb4ff3c4903114f1d
      Referenceadded
      —
      https://git.kernel.org/stable/c/547ef7e8cbb98f966c8719a3e15d4e078aaa9b47
      Referenceadded
      —
      https://git.kernel.org/stable/c/57177c5f47a8da852f8d76cf6945cf803f8bb9e5
      Referenceadded
      —
      https://git.kernel.org/stable/c/71a0fcb68c0a5f3ec912b540cd5d72148e6ee5f1
      Referenceadded
      —
      https://git.kernel.org/stable/c/a099834a51ccf9bbba3de86a251b3433539abfde
      Referenceadded
      —
      https://git.kernel.org/stable/c/b379b3162ff55a70464c6a934ae9bf0497478a62
      Referenceremoved
      https://git.kernel.org/stable/c/15a901361ec3fb1c393f91880e1cbf24ec0a88bd
      —
      Referenceremoved
      https://git.kernel.org/stable/c/26bb7d991f04eeef47dfad23e533834995c26f7a
      —
      Referenceremoved
      https://git.kernel.org/stable/c/53df27fd38f84bd3cd6b004eb4ff3c4903114f1d
      —
      Referenceremoved
      https://git.kernel.org/stable/c/547ef7e8cbb98f966c8719a3e15d4e078aaa9b47
      —
      Referenceremoved
      https://git.kernel.org/stable/c/57177c5f47a8da852f8d76cf6945cf803f8bb9e5
      —
      Referenceremoved
      https://git.kernel.org/stable/c/71a0fcb68c0a5f3ec912b540cd5d72148e6ee5f1
      —
      Referenceremoved
      https://git.kernel.org/stable/c/a099834a51ccf9bbba3de86a251b3433539abfde
      —
      Referenceremoved
      https://git.kernel.org/stable/c/b379b3162ff55a70464c6a934ae9bf0497478a62
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/15a901361ec3fb1c393f91880e1cbf24ec0a88bd Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/26bb7d991f04eeef47dfad23e533834995c26f7a Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/53df27fd38f84bd3cd6b004eb4ff3c4903114f1d Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/547ef7e8cbb98f966c8719a3e15d4e078aaa9b47 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/57177c5f47a8da852f8d76cf6945cf803f8bb9e5 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/71a0fcb68c0a5f3ec912b540cd5d72148e6ee5f1 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/a099834a51ccf9bbba3de86a251b3433539abfde Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/b379b3162ff55a70464c6a934ae9bf0497478a62 Types: Patch
      —

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

    3. Record modifiedCVE Program

      Show 4 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
      Referenceadded
      —
      https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
      Referenceremoved
      https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
      —
      Referenceremoved
      https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
      —

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

    4. Record modifiedSiemens ADP

      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/2025/21xxx/CVE-2025-21719.json">CVE-2025-21719</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-265688.html
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-784472.html
      Referenceremoved
      https://cert-portal.siemens.com/productcert/html/ssa-265688.html
      —

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

    5. Record modifiedLinux

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

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

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

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