Bug 2439931 (CVE-2026-23204)

Summary: CVE-2026-23204 kernel: net/sched: cls_u32: use skb_header_pointer_careful()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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Description OSIDB Bzimport 2026-02-14 17:03:39 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net/sched: cls_u32: use skb_header_pointer_careful()

skb_header_pointer() does not fully validate negative @offset values.

Use skb_header_pointer_careful() instead.

GangMin Kim provided a report and a repro fooling u32_classify():

BUG: KASAN: slab-out-of-bounds in u32_classify+0x1180/0x11b0
net/sched/cls_u32.c:221
Comment 1 TEJ RATHI 2026-02-16 06:36:43 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026021437-CVE-2026-23204-be85@gregkh/T