HighCVE-2024-26895

    Linux Kernel: Use-After-Free (CVE-2024-26895)

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

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    What is affected, what to do

    Update Linux Kernel to version 5.10.214, Linux Kernel to version 5.15.153, Linux Kernel to version 6.1.83.

    Affected
    • Linux Kernel lt 5.5..5.10.214
    • Linux Kernel lt 5.11..5.15.153
    • Linux Kernel lt 5.16..6.1.83
    • Linux Kernel lt 6.2..6.6.23
    • Linux Kernel lt 6.7..6.7.11
    • Linux Kernel lt 6.8..6.8.2
    Fixed in
    • Linux Kernel 5.10.214
    • Linux Kernel 5.15.153
    • Linux Kernel 6.1.83
    • Linux Kernel 6.6.23
    • Linux Kernel 6.7.11
    • Linux Kernel 6.8.2
    • Linux Kernel 6.9

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

    Metrics

    7.8

    XIEM Effective CVSS

    Highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    7.8

    CVSS v3

    Severity High on the scale from 0 to 10.

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

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 14.8

    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
    45.60 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
    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
    7.8 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
    7.8
    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
    0.2 %
    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
    14.8
    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 10 September 2024

    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:

    wifi: wilc1000: prevent use-after-free on vif when cleaning up all interfaces

    wilc_netdev_cleanup currently triggers a KASAN warning, which can be observed on interface registration error path, or simply by removing the module/unbinding device from driver:

    echo spi0.1 > /sys/bus/spi/drivers/wilc1000_spi/unbind

    ================================================================== BUG: KASAN: slab-use-after-free in wilc_netdev_cleanup+0x508/0x5cc Read of size 4 at addr c54d1ce8 by task sh/86

    CPU: 0 PID: 86 Comm: sh Not tainted 6.8.0-rc1+ #117 Hardware name: Atmel SAMA5 unwind_backtrace from show_stack+0x18/0x1c show_stack from dump_stack_lvl+0x34/0x58 dump_stack_lvl from print_report+0x154/0x500 print_report from kasan_report+0xac/0xd8 kasan_report from wilc_netdev_cleanup+0x508/0x5cc wilc_netdev_cleanup from wilc_bus_remove+0xc8/0xec wilc_bus_remove from spi_remove+0x8c/0xac spi_remove from device_release_driver_internal+0x434/0x5f8 device_release_driver_internal from unbind_store+0xbc/0x108 unbind_store from kernfs_fop_write_iter+0x398/0x584 kernfs_fop_write_iter from vfs_write+0x728/0xf88 vfs_write from ksys_write+0x110/0x1e4 ksys_write from ret_fast_syscall+0x0/0x1c

    [...]

    Allocated by task 1: kasan_save_track+0x30/0x5c __kasan_kmalloc+0x8c/0x94 __kmalloc_node+0x1cc/0x3e4 kvmalloc_node+0x48/0x180 alloc_netdev_mqs+0x68/0x11dc alloc_etherdev_mqs+0x28/0x34 wilc_netdev_ifc_init+0x34/0x8ec wilc_cfg80211_init+0x690/0x910 wilc_bus_probe+0xe0/0x4a0 spi_probe+0x158/0x1b0 really_probe+0x270/0xdf4 __driver_probe_device+0x1dc/0x580 driver_probe_device+0x60/0x140 __driver_attach+0x228/0x5d4 bus_for_each_dev+0x13c/0x1a8 bus_add_driver+0x2a0/0x608 driver_register+0x24c/0x578 do_one_initcall+0x180/0x310 kernel_init_freeable+0x424/0x484 kernel_init+0x20/0x148 ret_from_fork+0x14/0x28

    Freed by task 86: kasan_save_track+0x30/0x5c kasan_save_free_info+0x38/0x58 __kasan_slab_free+0xe4/0x140 kfree+0xb0/0x238 device_release+0xc0/0x2a8 kobject_put+0x1d4/0x46c netdev_run_todo+0x8fc/0x11d0 wilc_netdev_cleanup+0x1e4/0x5cc wilc_bus_remove+0xc8/0xec spi_remove+0x8c/0xac device_release_driver_internal+0x434/0x5f8 unbind_store+0xbc/0x108 kernfs_fop_write_iter+0x398/0x584 vfs_write+0x728/0xf88 ksys_write+0x110/0x1e4 ret_fast_syscall+0x0/0x1c [...]

    David Mosberger-Tan initial investigation [1] showed that this use-after-free is due to netdevice unregistration during vif list traversal. When unregistering a net device, since the needs_free_netdev has been set to true during registration, the netdevice object is also freed, and as a consequence, the corresponding vif object too, since it is attached to it as private netdevice data. The next occurrence of the loop then tries to access freed vif pointer to the list to move forward in the list.

    Fix this use-after-free thanks to two mechanisms:

    • navigate in the list with list_for_each_entry_safe, which allows to safely modify the list as we go through each element. For each element, remove it from the list with list_del_rcu
    • make sure to wait for RCU grace period end after each vif removal to make sure it is safe to free the corresponding vif too (through unregister_netdev)

    Since we are in a RCU "modifier" path (not a "reader" path), and because such path is expected not to be concurrent to any other modifier (we are using the vif_mutex lock), we do not need to use RCU list API, that's why we can benefit from list_for_each_entry_safe.

    [1] https://lore.kernel.org/linux-wireless/ab077dbe58b1ea5de0a3b2ca21f275a07af967d2.camel@egauge.net/

    Source: siemens_advisory, suse_csaf, Debian Security Advisories, BSI CSAF, BSI WID Portal, NVD (NIST), cvelistv5, 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
    • 6.8 – < 6.8.2
    • 5.11 – < 5.15.153
    • 5.16 – < 6.1.83
    • —
    • 5.5 – < 5.10.214
    • 6.2 – < 6.6.23
    • 6.7 – < 6.7.11
    • 6.8.2
    • 5.15.153
    • 6.1.83
    • 6.9
    • 5.10.214
    • 6.6.23
    • 6.7.11

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebiandebian_linux10.0
    Linuxdebianlinuxbullseye
    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 modifiedLinux

      Show 21 original changes
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      https://git.kernel.org/stable/c/24228dcf1d30c2231caa332be7d3090ac59fbfe9
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      https://git.kernel.org/stable/c/3da9d32b7f4a1a9f7e4bb15bb82f2b2dd6719447
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      https://git.kernel.org/stable/c/5956f4203b6cdd0755bbdd21b45f3933c7026208
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      https://git.kernel.org/stable/c/73a2aa0aef86c2c07be5a2f42c9e6047e1a2f7bb
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      https://git.kernel.org/stable/c/a9545af2a533739ffb64d6c9a6fec6f13e2b505f
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      https://git.kernel.org/stable/c/cb5942b77c05d54310a0420cac12935e9b6aa21c
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      https://git.kernel.org/stable/c/fe20e3d56bc911408fc3c27a17c59e9d7885f7d1
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      https://git.kernel.org/stable/c/24228dcf1d30c2231caa332be7d3090ac59fbfe9
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      https://git.kernel.org/stable/c/24228dcf1d30c2231caa332be7d3090ac59fbfe9 Types: Patch
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      https://git.kernel.org/stable/c/5956f4203b6cdd0755bbdd21b45f3933c7026208 Types: Patch
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      https://git.kernel.org/stable/c/fe20e3d56bc911408fc3c27a17c59e9d7885f7d1 Types: Patch
      —

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

    2. Record modifiedCVE Program

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      https://git.kernel.org/stable/c/24228dcf1d30c2231caa332be7d3090ac59fbfe9
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      https://git.kernel.org/stable/c/3da9d32b7f4a1a9f7e4bb15bb82f2b2dd6719447
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      https://git.kernel.org/stable/c/5956f4203b6cdd0755bbdd21b45f3933c7026208
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      https://git.kernel.org/stable/c/73a2aa0aef86c2c07be5a2f42c9e6047e1a2f7bb
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      https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html
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      https://git.kernel.org/stable/c/24228dcf1d30c2231caa332be7d3090ac59fbfe9 Types: Patch
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      https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html Types: Mailing List
      —

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

    3. Record modifiedSiemens ADP

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      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2024/26xxx/CVE-2024-26895.json">CVE-2024-26895</a>
      Referenceadded
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      https://cert-portal.siemens.com/productcert/html/ssa-265688.html
      Referenceremoved
      https://cert-portal.siemens.com/productcert/html/ssa-265688.html
      —

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

    4. Record modifiedLinux

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

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      AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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

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