CVE-2026-43039

CVE-2026-43039 is a critical-severity vulnerability in Linux Linux Kernel with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low.

Key facts

Description

In the Linux kernel, the following vulnerability has been resolved: net: ti: icssg-prueth: fix missing data copy and wrong recycle in ZC RX dispatch emac_dispatch_skb_zc() allocates a new skb via napi_alloc_skb() but never copies the packet data from the XDP buffer into it. The skb is passed up the stack containing uninitialized heap memory instead of the actual received packet, leaking kernel heap contents to userspace. Copy the received packet data from the XDP buffer into the skb using skb_copy_to_linear_data(). Additionally, remove the skb_mark_for_recycle() call since the skb is backed by the NAPI page frag allocator, not page_pool. Marking a non-page_pool skb for recycle causes the free path to return pages to a page_pool that does not own them, corrupting page_pool state. The non-ZC path (emac_rx_packet) does not have these issues because it uses napi_build_skb() to wrap the existing page_pool page directly, requiring no copy, and correctly marks for recycle since the page comes from page_pool_dev_alloc_pages().

Frequently asked questions

What is CVE-2026-43039?
In the Linux kernel, the following vulnerability has been resolved: net: ti: icssg-prueth: fix missing data copy and wrong recycle in ZC RX dispatch emac_dispatch_skb_zc() allocates a new skb via napi_alloc_skb() but never copies the packet data from the XDP buffer into it. The skb is passed up the stack containing uninitialized heap memory instead of the actual received packet, leaking kernel heap contents to userspace. Copy the received packet data from the XDP buffer into the skb using skb_copy_to_linear_data(). Additionally, remove the skb_mark_for_recycle() call since the skb is backed by the NAPI page frag allocator, not page_pool. Marking a non-page_pool skb for recycle causes the free path to return pages to a page_pool that does not own them, corrupting page_pool state. The non-ZC path (emac_rx_packet) does not have these issues because it uses napi_build_skb() to wrap the existing page_pool page directly, requiring no copy, and correctly marks for recycle since the page comes from page_pool_dev_alloc_pages().
How severe is CVE-2026-43039?
CVE-2026-43039 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-43039 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-43039?
CVE-2026-43039 primarily affects Linux Linux Kernel. In total, 7 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-43039?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
Does CVE-2026-43039 have an EU (EUVD) identifier?
Yes. CVE-2026-43039 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-26638.
When was CVE-2026-43039 published?
CVE-2026-43039 was published on 2026-05-01 and last updated on 2026-06-17.

References

Affected products (7)

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