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CVE-2026-90250: bpf, cgroup: Fix storage null-ptr-deref after replacing prog

• Severity: unknown
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-17 · updated 2026-10-30

Description

In the Linux kernel, the following vulnerability has been resolved: bpf, cgroup: Fix storage null-ptr-deref after replacing prog Syzkaller reported a storage null-ptr-deref issue after replacing prog. This occurs in the following scenario: 1. prog A, an empty prog, is attached to a cgrp. 2. prog B uses BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE and calls the bpf_get_local_storage helper. 3. link_update is called to replace prog A with prog B. The reason is that __cgroup_bpf_replace fails to alloc and assign the required cgrp storage for the incoming replacement prog. Consequently, the new prog inherits an uninit storage, leading to null-ptr-deref panic when kick the new prog. Fix this by rejecting a link update if new_prog's cgroup storage is incompatible with link->prog.

Affected products

• Linux: 5.7 — fixed in 7.3

How to fix

Upgrade to a fixed version: Linux 7.3. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/12feca126831556dc7fabe5a3ba28fbd328768b6
• https://git.kernel.org/stable/c/16c8321ee40c420f8e02e09515a5126682ddf4ea
• https://git.kernel.org/stable/c/1ab3da12061d7ccb099f7e925fa2d865967a316a
• https://git.kernel.org/stable/c/3f562c537e9ecf4bc5e206cfffc2cc047f1b7e94
• https://git.kernel.org/stable/c/85785e7e2ebddcaa5c3b31bd3bcd83ae648985d4
• https://git.kernel.org/stable/c/a033c950f6731be88a7da98604ed78f302f15b80

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