cbcvebase.
CVE-2026-23319
published 2026-03-25

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 of this bug is that…

PriorityP339high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.13%
2.6th percentile
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.

Affected

51 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.19.8-1 (forky)linux 6.19.8-1 (forky)
linuxlinux
linuxlinux>= 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 529e685e522b9d7fb379dbe6929dcdf520e34c8c529e685e522b9d7fb379dbe6929dcdf520e34c8c
linuxlinux>= 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 9b02c5c4147f8af8ed783c8deb5df927a55c39519b02c5c4147f8af8ed783c8deb5df927a55c3951
linuxlinux>= 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < cfcfa0ca0212162aa472551266038e8fd6768cffcfcfa0ca0212162aa472551266038e8fd6768cff
linuxlinux>= 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 3eeddb80191f7626ec1ef742bfff51ec3b0fa5c23eeddb80191f7626ec1ef742bfff51ec3b0fa5c2
linuxlinux>= 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 4e8a0005d633a4adc98e3b65d5080f93b90d356b4e8a0005d633a4adc98e3b65d5080f93b90d356b
linuxlinux>= 69fd337a975c7e690dfe49d9cb4fe5ba1e6db44e < 56145d237385ca0e7ca9ff7b226aaf2eb8ef368b56145d237385ca0e7ca9ff7b226aaf2eb8ef368b
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.19.8-16.19.8-1
linuxlinux_kernel>= 6.0.0 < 6.1.1676.1.167
linuxlinux_kernel>= 6.0.1 < 6.1.1676.1.167
linuxlinux_kernel>= 6.13 < 6.18.176.18.17
linuxlinux_kernel>= 6.13.0 < 6.18.176.18.17
linuxlinux_kernel>= 6.19 < 6.19.76.19.7
linuxlinux_kernel>= 6.19.0 < 6.19.76.19.7
linuxlinux_kernel>= 6.2 < 6.6.1306.6.130
linuxlinux_kernel>= 6.2.0 < 6.6.1306.6.130

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vendor_redhat6.4MEDIUM
vendor_msrc5.5MEDIUM
vendor_ubuntu2.0LOW
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