CVE-2026-23319

Siemens ProductCERT Advisory SSA-019113

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim The root cause of this bug is that when 'bpf_link_put' reduces the refcount of 'shim_link->link.link' to zero, the resource is considered released but may still be referenced via 'tr->progs_hlist' in 'cgroup_shim_find'. The actual cleanup of 'tr->progs_hlist' in 'bpf_shim_tramp_link_release' is deferred. During this window, another process can cause a use-after-free via 'bpf_trampoline_link_cgroup_shim'. Based on Martin KaFai Lau's suggestions, I have created a simple patch. To fix this: Add an atomic non-zero check in 'bpf_trampoline_link_cgroup_shim'. Only increment the refcount if it is not already zero. Testing: I verified the fix by adding a delay in 'bpf_shim_tramp_link_release' to make the bug easier to trigger: static void bpf_shim_tramp_link_release(struct bpf_link *link) { /* ... */ if (!shim_link->trampoline) return; + msleep(100); WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link, shim_link->trampoline, NULL)); bpf_trampoline_put(shim_link->trampoline); } Before the patch, running a PoC easily reproduced the crash(almost 100%) with a call trace similar to KaiyanM's report. After the patch, the bug no longer occurs even after millions of iterations.

Metrics

Severity
high
no public PoC known
7.8
Source: nvd-v3
2.6 %
Low — this CVE sits in the lower 10% of all CVEs scored today.
0.1 %
Low — model estimates < 1% exploitation likelihood.
Published
2021-09-26 00:00 UTC

Affected operating systems

  • linux

    amazon / amazon_linux

  • linux

    ubuntu / awsbionic

  • linux

    ubuntu / awsjammy

  • linux

    ubuntu / awsnoble

  • linux

    ubuntu / awsresolute

  • linux

    ubuntu / awsxenial

  • linux

    ubuntu / aws-6.8jammy

  • linux

    ubuntu / aws-hwexenial

  • linux

    ubuntu / azurejammy

  • linux

    ubuntu / azurenoble

  • linux

    ubuntu / azureresolute

  • linux

    ubuntu / azurexenial

  • linux

    ubuntu / azure-4.15bionic

  • linux

    suse / basesystem_module15

  • linux

    debian / debian_linux11.0

  • linux

    debian / debian_linux12.0

  • linux

    debian / debian_linux13.0

  • linux

    suse / development_tools_module15

  • linux

    redhat / enterprise_linux10.0

  • linux

    redhat / enterprise_linux7.0

  • linux

    redhat / enterprise_linux8.0

  • linux

    redhat / enterprise_linux9.0

  • linux

    redhat / enterprise_linux_aus8.4

  • linux

    redhat / enterprise_linux_aus8.6

Affected products

Products and version ranges extracted from the vendor/CERT advisory. A range like „<4.14.6“ implies the update recommendation „upgrade to 4.14.6 or later“.

  • arista

    cloudvision_agni2024.4.0 – 2025.2.2

  • arista

    cloudvision_portal2024.2.0 – 2026.1.0

  • arista

    velocloud_edge4.5.0 – 6.4.1

  • arista

    velocloud_gateway

  • arista

    velocloud_orchestrator

  • canonical

    ubuntu_linux

  • Citrix Systems

    Hypervisor8.2 CU1 LTSR

  • Citrix Systems

    XenServer8.4

  • Dell

    ECS3.8.1.0-3.8.1.7

  • Dell

    NetWorkerVirtual Edition

  • Dell

    NetWorkervProxy 19.13.0.3

  • Dell

    NetWorkervProxy 19.14

  • Dell

    PowerScale OneFS13.2.3

  • Dell

    PowerScale OneFSOneFS

  • Dell

    Secure Connect GatewayAppliance 5.32.00.18

  • gnupg

    libgcrypt1.11.0 – 1.11.3

  • gnupg

    libgcrypt1.12.0 – 1.12.2

  • gnupg

    libgcrypt1.8.8 – 1.10.4

  • Intel

    ProzessorCore Ultra 5

  • Intel

    ProzessorCore Ultra 7

  • Intel

    ProzessorCore Ultra 9

  • julia

    openssh_jll

  • netapp

    active_iq_unified_manager

  • netapp

    clustered_data_ontap

References & sources

Linked CVEs

Show 406 more CVEs
IDCVE-2026-23319
Siemens ProductCERT Advisory SSA-019113 — CVE-2026-23319 | NEOSEC Intel