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.
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.
Review the upstream advisory, identify the affected product in your inventory, and apply the vendor update when one is available.
CVE-2026-23319 is listed in the HOL Guard supply-chain feed, but affected software is not mapped to a package. Review the upstream advisory for the affected product and vendor guidance. 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 software not mapped. Review the upstream record for vendor-specific product and version guidance.
Reported by NVD (nvd).
HOL Guard can help your team monitor supply-chain activity while the upstream record is clarified.
Explore HOL GuardReview the upstream advisory, identify the affected product in your inventory, and apply the vendor update when one is available.
CVE-2026-23319 is listed in the HOL Guard supply-chain feed, but affected software is not mapped to a package. Review the upstream advisory for the affected product and vendor guidance. 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 software not mapped. Review the upstream record for vendor-specific product and version guidance.
Reported by NVD (nvd).
HOL Guard can help your team monitor supply-chain activity while the upstream record is clarified.
Explore HOL Guard