CVE WatchOct 15, 2026

CVE-2026-23319

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix a UAF issue in bpf_trampoline_link_cgroup_shim The root cause

CVSS

7.8

High

EPSS

0.1%

KEV

—

Exploit Today

0-100

Published: Mar 25, 2026 · Last modified: Oct 15, 2026 · CWE-416

EPSS · 30d

0.1%EPSS · 30 days0.1%

2026-09-282026-10-26

Technical 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.

Official references

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CVE-2026-869167.8 HIG

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——0A use after free issue was addressed with improved memory management. This issue is fixed in iOS 26.7 and iPadOS 26.7, iOS 27 and iPadOS 27, macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7.2. An app may be able to execute arbitrary code with kernel privileges.3h CVE-2026-1126558.8 HIG

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——0A use-after-free issue was addressed with improved memory management. This issue is fixed in Safari 27.2, iOS 26.7.2 and iPadOS 26.7.2, iOS 27.2 and iPadOS 27.2, macOS Golden Gate 27.2, tvOS 27.2, visionOS 27.2, watchOS 27.2. Processing maliciously crafted web content may lead to arbitrary code execution.3h CVE-2026-1126518.8 HIG

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——0A use-after-free issue was addressed with improved memory management. This issue is fixed in Safari 27.2, iOS 26.7.2 and iPadOS 26.7.2, iOS 27.2 and iPadOS 27.2, macOS Golden Gate 27.2, visionOS 27.2. Processing maliciously crafted web content may lead to arbitrary code execution.3h CVE-2026-1126378.8 HIG

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——0A use-after-free issue was addressed with improved memory management. This issue is fixed in Safari 27.2, iOS 27.2 and iPadOS 27.2, macOS Golden Gate 27.2, tvOS 27.2, visionOS 27.2, watchOS 27.2. Processing maliciously crafted web content may lead to arbitrary code execution.3h CVE-2026-1126268.8 HIG

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——0A use-after-free issue was addressed with improved memory management. This issue is fixed in Safari 27.2, iOS 26.7.2 and iPadOS 26.7.2, iOS 27.2 and iPadOS 27.2, macOS Golden Gate 27.2, visionOS 27.2. Processing maliciously crafted web content may lead to arbitrary code execution.3h