CVE-2026-98368

7.8 HIGH

Published 2026-10-06 · Updated 2026-10-07

AI risk analysis

Summary: The Linux kernel's ESP (Encapsulating Security Payload) implementation fails to properly handle zerocopy managed fragments, leading to potential use-after-free conditions and memory leaks when processing network packets. This occurs because ESP mutates fragment arrays without downgrading managed fragment references, breaking critical invariants that protect zero-copy page management.
Exploitability: Exploitation is moderately difficult and requires specific conditions including the use of zerocopy managed fragments with ESP encryption, but does not require user interaction or privilege escalation.
Blast radius: The vulnerability could affect network-intensive applications using ESP encryption, potentially causing system instability, memory corruption, or denial of service through memory leaks and use-after-free conditions in kernel memory management.
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Apply the kernel patch that implements skb_zcopy_downgrade_managed() before ESP modifies fragment arrays, specifically targeting the fix for CVE-2026-98368 which addresses the zerocopy managed frag handling in ESP output processing.

kernelnetworkmemory-corruptionesp

Analysis generated locally by garnet-coder (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

In the Linux kernel, the following vulnerability has been resolved: esp: downgrade zerocopy managed frags before mutating skb frags On the out-of-place output path (esp->inplace == false) ESP rewrites the skb frag array: esp_output_head() appends a trailer frag and esp_output_tail() replaces the frags with a destination page, both referenced with get_page(). When the skb carries zerocopy managed frags (SKBFL_MANAGED_FRAG_REFS) the payload frags are owned by the ubuf and must not be referenced or unreferenced individually, but ESP mutates the frag array without ever downgrading the skb. This breaks the managed-frag invariant two ways: - esp_ssg_unref() walks the source scatterlist and drops a page reference for every frag, including the ubuf-owned payload frags, pushing their refcount below the GUP pin bias while the pages are still pinned, i.e. a use-after-free of the zerocopy pages; - esp_output_tail() installs its destination page as frag 0 with get_page() but leaves SKBFL_MANAGED_FRAG_REFS set, so skb_release_data() takes the skip_unref branch and never drops that reference, leaking the x->xfrag page at packet rate. Fix this the way every other frag-mutating site does (__ip_append_data(), __ip6_append_data(), tcp_sendmsg_locked()) and call skb_zcopy_downgrade_managed() before ESP touches the frag array: it takes a real reference on each existing frag and clears SKBFL_MANAGED_FRAG_REFS, so the per-frag unref in esp_ssg_unref() and the frag release in skb_release_data() are both balanced and no mixed-ownership frag array is left behind.

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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